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Factor IX, also known as Christmas factor, is a protein that functions as a serine protease and is essential for blood coagulation.
Answer: True
Factor IX is a protein that functions as a serine protease and plays a critical role in the blood coagulation cascade, which is essential for hemostasis.
Factor IX was named Christmas factor after the scientist who discovered it, Dr. Stephen Christmas.
Answer: False
Factor IX is known as Christmas factor because it was first identified in a patient named Stephen Christmas, not after the scientist who discovered it.
Factor IX is primarily found within the nucleus and mitochondria of cells.
Answer: False
Factor IX is primarily synthesized in the liver and secreted into the bloodstream, functioning extracellularly within the coagulation cascade. It is not predominantly localized to the nucleus or mitochondria.
Factor IX is involved in biological processes such as hemostasis and blood coagulation.
Answer: True
Hemostasis and blood coagulation are the principal biological processes in which Factor IX plays a vital role as a key component of the coagulation cascade.
Being a serine protease means Factor IX utilizes a cysteine residue in its active site for catalysis.
Answer: False
Serine proteases, by definition, utilize a serine residue within their catalytic triad for enzymatic activity. Cysteine proteases utilize a cysteine residue.
The alternative name for Factor IX, Christmas factor, originates from the location where it was discovered.
Answer: False
The name 'Christmas factor' derives from the surname of the first patient identified with a deficiency in this clotting factor, not from a geographical location.
Factor IX is involved in signal peptide processing.
Answer: True
Factor IX participates in biological processes including signal peptide processing, which is integral to its synthesis and secretion pathway.
What is the primary role of Factor IX in the human body?
Answer: Acting as a serine protease in the blood coagulation cascade.
Factor IX functions as a serine protease, playing a crucial role in the intrinsic pathway of the blood coagulation cascade, which ultimately leads to the formation of a stable fibrin clot.
Why is Factor IX also known as Christmas factor?
Answer: It was first identified in a patient named Stephen Christmas.
The designation 'Christmas factor' originates from the surname of the first patient in whom a deficiency of this clotting factor was identified.
In which cellular component is Factor IX primarily localized, according to the source?
Answer: Extracellular space
Factor IX functions primarily in the extracellular space as a component of the blood coagulation cascade, although its synthesis occurs intracellularly before secretion.
Factor IX is synthesized in the body in its active form, Factor IXa, directly upon translation.
Answer: False
Factor IX is synthesized as an inactive precursor known as a zymogen (Factor IX). It requires post-translational modifications and subsequent enzymatic cleavage to become activated into its functional form, Factor IXa.
Factor IX can only be activated by Factor XIa, which is part of the intrinsic pathway of coagulation.
Answer: False
Factor IX can be activated by both Factor XIa (intrinsic pathway) and Factor VIIa (extrinsic pathway), indicating its central role in integrating different coagulation pathways.
Once activated to Factor IXa, it requires Factor VIII as a cofactor to form a complex that activates Factor X.
Answer: True
Activated Factor IX (Factor IXa), in conjunction with its cofactor Factor VIII, forms a complex on phospholipid surfaces that significantly enhances the activation of Factor X.
Antithrombin is a substance that promotes the activity of Factor IX.
Answer: False
Antithrombin functions as a natural anticoagulant by inhibiting the activity of several coagulation factors, including Factor IXa, thereby preventing excessive clot formation.
Factor VIII acts as a substrate for Factor IXa in the coagulation cascade.
Answer: False
Factor VIII functions as a cofactor for Factor IXa, enhancing its enzymatic activity. Factor X is the primary substrate activated by the Factor IXa-Factor VIII complex.
The term 'zymogen' implies that Factor IX is produced in an active enzymatic form.
Answer: False
A zymogen is an inactive precursor form of an enzyme. Factor IX is synthesized as a zymogen and requires proteolytic cleavage to become enzymatically active.
Factor IX's role in activating Factor X is facilitated by calcium ions and membrane phospholipids.
Answer: True
The activation of Factor X by the Factor IXa-Factor VIII complex is critically dependent on the presence of calcium ions and membrane phospholipids, which provide a surface for complex assembly and function.
How is Factor IX initially synthesized within the body?
Answer: As a zymogen, which is an inactive precursor.
Factor IX is synthesized in the liver as an inactive zymogen precursor. It undergoes post-translational modifications and subsequent activation steps to become functional.
Factor IX can be activated into its functional form, Factor IXa, by which of the following factors?
Answer: Factor XIa and Factor VIIa
Factor IX can be activated by cleavage by Factor XIa (intrinsic pathway) or Factor VIIa (extrinsic pathway), demonstrating its integration into multiple coagulation routes.
What is the role of Factor VIII in conjunction with Factor IXa?
Answer: Factor VIII serves as a cofactor to enhance the activation of Factor X by Factor IXa.
Factor VIII acts as an essential cofactor for Factor IXa. Together, they form a complex that significantly amplifies the activation of Factor X, a critical step in the coagulation cascade.
Which protein acts as an inhibitor of Factor IX activity?
Answer: Antithrombin
Antithrombin is a key physiological inhibitor of coagulation factors, including Factor IXa, playing a vital role in regulating the clotting process and preventing thrombosis.
Factor IX expression levels have been observed to decrease with age in both humans and mice.
Answer: False
Research indicates that Factor IX expression levels may increase with age in certain contexts, rather than decrease. The regulatory mechanisms are complex and subject to ongoing investigation.
The Factor IX protein consists of four main structural domains: Gla, two EGF-like domains, and a trypsin-like peptidase domain.
Answer: True
The mature Factor IX protein is structurally characterized by an N-terminal Gla domain, two tandem EGF (Epidermal Growth Factor)-like domains, and a C-terminal trypsin-like peptidase domain.
The N-terminal Gla domain of Factor IX is primarily involved in binding to tissue factor.
Answer: False
The N-terminal Gla domain is crucial for calcium-dependent binding to phospholipid surfaces. Binding to tissue factor is primarily mediated by the EGF-like domains.
The Gla domain of Factor IX is essential for its calcium-dependent binding to phospholipid surfaces.
Answer: True
The gamma-carboxyglutamic acid (Gla) domain is post-translationally modified and is critical for mediating the calcium-dependent interaction of Factor IX with negatively charged phospholipid membranes, such as those found on activated platelets.
The gene responsible for Factor IX, F9, is located on the Y chromosome.
Answer: False
The F9 gene, which encodes Factor IX, is located on the X chromosome, not the Y chromosome.
Factor IX deficiency is considered an X-linked recessive disorder because the F9 gene is on the X chromosome.
Answer: True
The X-linked recessive inheritance pattern of Factor IX deficiency arises because the F9 gene is located on the X chromosome. Males, possessing only one X chromosome, are more susceptible to expressing the disorder if they inherit a mutation.
The C-terminal trypsin-like peptidase domain of Factor IX is the catalytic domain, responsible for enzymatic cleavage.
Answer: True
The trypsin-like peptidase domain constitutes the catalytic core of Factor IX, enabling it to cleave specific peptide bonds in substrate molecules during the coagulation cascade.
The F9 gene is located on the X chromosome at band Xq27.1 in humans.
Answer: True
The human F9 gene, responsible for Factor IX synthesis, is precisely mapped to the X chromosome at band Xq27.1.
The human F9 gene spans approximately 32 kilobases on the X chromosome.
Answer: True
The genomic sequence of the human F9 gene spans approximately 32 kilobases on the X chromosome, encompassing its exons and introns.
The orthologous F9 gene in mice is located on chromosome 1.
Answer: False
The orthologous F9 gene in mice is located on the X chromosome, similar to its human counterpart, not on chromosome 1.
The F9 gene spans from base pair 59,044,824 to 59,076,119 on chromosome X in mice.
Answer: True
According to genomic databases, the mouse F9 gene is located on chromosome X within the specified base pair range.
Factor IX deficiency is more commonly diagnosed in females than males due to its X-linked recessive nature.
Answer: False
Due to the X-linked recessive inheritance pattern, Factor IX deficiency is diagnosed significantly more frequently in males than in females.
Which of the following is NOT one of the four main protein domains of Factor IX?
Answer: Kringle domain
The Factor IX protein structure comprises a Gla domain, two EGF-like domains, and a trypsin-like peptidase domain. Kringle domains are found in other proteins, such as Factor XIII, but not in Factor IX.
The N-terminal EGF-like domain of Factor IX is primarily associated with binding to which molecule?
Answer: Tissue factor
The EGF-like domains of Factor IX are implicated in interactions with tissue factor, which plays a role in the extrinsic pathway of coagulation, and also in mediating interactions with platelets.
What is the crucial function of the Gla domain in Factor IX?
Answer: Facilitating calcium-dependent binding to phospholipid surfaces.
The Gla domain is essential for Factor IX's ability to bind to negatively charged phospholipid surfaces in a calcium-dependent manner, which is critical for its localization and function within the coagulation complex.
Where is the gene responsible for producing Factor IX (F9) located in the human genome?
Answer: The X chromosome
The F9 gene, encoding Factor IX, is located on the X chromosome at band Xq27.1.
Why is Factor IX deficiency classified as an X-linked recessive disorder?
Answer: The F9 gene is located on the X chromosome, and males have only one copy.
The X-linked recessive nature stems from the F9 gene's location on the X chromosome. Males, having only one X chromosome, will express the deficiency if they inherit a mutated allele, whereas females typically require two mutated alleles.
The C-terminal trypsin-like peptidase domain of Factor IX is responsible for:
Answer: The enzymatic cleavage of other proteins in the cascade.
The trypsin-like peptidase domain is the catalytic center of Factor IX, enabling it to perform enzymatic cleavage of target substrates, most notably Factor X, within the coagulation cascade.
The F9 gene spans from base pair 139,530,739 to 139,563,459 on the human X chromosome. What is the approximate length of the gene?
Answer: Approximately 33 kilobases
Calculating the difference between the end and start base pair positions (139,563,459 - 139,530,739) yields approximately 32,720 base pairs, which is approximately 33 kilobases.
A deficiency in Factor IX causes hemophilia A, while a deficiency in Factor VIII causes hemophilia B.
Answer: False
This statement is factually incorrect. A deficiency in Factor IX results in hemophilia B (Christmas disease), whereas a deficiency in Factor VIII causes hemophilia A.
Fewer than 100 disease-causing mutations in the F9 gene have been identified.
Answer: False
A substantial number of disease-causing mutations have been identified in the F9 gene; the source indicates at least 534 variants have been documented.
Mutations in the Factor IX gene can only lead to a deficiency, never to an increased risk of clotting.
Answer: False
Certain rare mutations in the F9 gene can result in a gain-of-function, leading to a hyperfunctional Factor IX protein and an increased risk of thrombophilia (excessive clotting).
The Factor IX Padua mutation is associated with a reduced risk of blood clotting.
Answer: False
The Factor IX Padua mutation is a gain-of-function mutation that results in a hyperfunctional enzyme, thereby increasing the risk of blood clotting (thrombophilia).
Which medical condition is directly caused by a deficiency in Factor IX?
Answer: Hemophilia B (Christmas disease)
A deficiency in Factor IX is the direct cause of hemophilia B, also known clinically as Christmas disease, characterized by impaired blood clotting.
How many disease-causing mutations in the F9 gene have been identified according to the source?
Answer: At least 534
The source indicates that a substantial number of disease-causing mutations have been identified in the F9 gene, with at least 534 variants documented.
Rare mutations in the Factor IX gene can lead to a gain-of-function, resulting in:
Answer: An increased risk of blood clot formation (thrombophilia).
Gain-of-function mutations in the F9 gene can result in a hyperfunctional Factor IX protein, leading to an elevated risk of thrombosis, a condition known as thrombophilia.
Factor IX is classified under the Enzyme Commission (EC) number 3.4.21.22.
Answer: True
The Enzyme Commission (EC) number 3.4.21.22 is indeed assigned to Factor IX, classifying it as a serine-type endopeptidase.
The primary gene symbol for Factor IX is F9, but it is also known by aliases such as FIX and PTC.
Answer: True
The gene encoding Factor IX is officially designated F9. Common aliases include FIX and PTC, among others.
The Protein Data Bank (PDB) does not contain any structural information for Factor IX.
Answer: False
The Protein Data Bank (PDB) contains numerous entries detailing the three-dimensional structures of Factor IX and its various forms, crucial for structural biology research.
Gene Ontology attributes hydrolase activity and calcium ion binding to Factor IX.
Answer: True
Gene Ontology annotations confirm that Factor IX possesses hydrolase activity and is involved in calcium ion binding, reflecting its biochemical functions.
Amigo and QuickGO are primary sources for Gene Ontology information regarding Factor IX.
Answer: True
Amigo and QuickGO are indeed recognized as primary databases and interfaces for accessing Gene Ontology (GO) annotations, including those pertaining to Factor IX.
The Entrez Gene ID for human Factor IX is 14071.
Answer: False
The Entrez Gene ID for human Factor IX is 2158. The ID 14071 corresponds to mouse Factor IX.
The UniProt accession number P00740 corresponds to mouse Factor IX.
Answer: False
The UniProt accession number P00740 is assigned to human Factor IX. The corresponding accession number for mouse Factor IX is P16294.
The PDB structure 1cfi illustrates the human coagulation Factor IXa in complex with p-aminobenzamidine.
Answer: False
PDB structure 1cfi depicts the calcium ion-bound gamma-carboxyglutamic acid-rich (Gla) domain of Factor IX, not the activated Factor IXa in complex with p-aminobenzamidine. Structure 1rfn, for instance, depicts Factor IXa in complex with p-aminobenzamidine.
The EAHAD database compiles information on mutations found in the Factor IX gene.
Answer: True
The European Association for Haemophilia and Allied Disorders (EAHAD) maintains a database dedicated to cataloging mutations identified within the Factor IX gene.
According to MEROPS, Factor IX is classified as a cysteine protease.
Answer: False
The MEROPS database classifies Factor IX as a serine protease, reflecting the presence of a serine residue in its catalytic active site.
The PDB structure 1edm provides insights into the EGF-like domains of Factor IX.
Answer: True
The Protein Data Bank structure 1edm offers valuable insights into the structural characteristics and potential functions of the Epidermal Growth Factor (EGF)-like domains within the Factor IX protein.
The PDB structure 1rfn shows Factor IX in its inactive zymogen form.
Answer: False
PDB structure 1rfn illustrates the activated form of Factor IX (Factor IXa) in complex with p-aminobenzamidine, providing insights into its active site, not its inactive zymogen form.
The RefSeq accession number NM_000133 is for mouse Factor IX mRNA.
Answer: False
The RefSeq accession number NM_000133 corresponds to human Factor IX mRNA. The accession number for mouse Factor IX mRNA is NM_007979.
What does the EC number 3.4.21.22 signify for Factor IX?
Answer: Its primary function as a serine protease.
The EC number 3.4.21.22 classifies Factor IX as a serine-type endopeptidase, indicating its enzymatic function and the catalytic residue involved.
Which of the following is an alias for the Factor IX gene?
Answer: PTC
PTC (Plasma Thromboplastin Component) is a known alias for the Factor IX gene (F9).
Which PDB structure mentioned in the source illustrates the active site of Factor IXa interacting with a potential inhibitor?
Answer: 1rfn
The Protein Data Bank (PDB) structure 1rfn depicts the human coagulation Factor IXa in complex with p-aminobenzamidine, offering insights into its active site and inhibitor interactions.
According to Gene Ontology, Factor IX exhibits which molecular function?
Answer: Endopeptidase activity
Gene Ontology annotations classify Factor IX as possessing endopeptidase activity, reflecting its role as an enzyme that cleaves internal peptide bonds.
What is the Entrez Gene ID for human Factor IX?
Answer: 2158
The Entrez Gene ID for the human F9 gene, which encodes Factor IX, is 2158.
Which of the following is a correct RefSeq accession number for human Factor IX mRNA?
Answer: NM_000133
NM_000133 is a valid RefSeq accession number for human Factor IX mRNA. NM_007979 and NM_001305797 are associated with mouse Factor IX mRNA.
What is the primary classification of Factor IX within the MEROPS database?
Answer: Serine protease
The MEROPS database classifies Factor IX as a serine protease, reflecting its enzymatic mechanism involving a serine residue in the active site.
Factor IX is listed on the World Health Organization's List of Essential Medicines due to its critical role in treating specific conditions.
Answer: True
The inclusion of Factor IX on the World Health Organization's List of Essential Medicines underscores its critical importance in the management of specific medical conditions, ensuring its availability for patient care.
Kotoku Kurachi and Earl Davie are credited with cloning the F9 gene in 1982.
Answer: True
The seminal work of cloning the F9 gene was accomplished by Kotoku Kurachi and Earl Davie in 1982, representing a significant advancement in understanding Factor IX genetics.
Polly, a sheep cloned by Ian Wilmut, was genetically engineered to produce human Factor IX.
Answer: True
The transgenic sheep named Polly, developed by Ian Wilmut's team, was engineered to express the human Factor IX gene, demonstrating the potential for producing therapeutic proteins in livestock.
Nonacog alfa (Benefix) and albutrepenonacog alfa (Idelvion) are brand names for recombinant Factor IX treatments.
Answer: True
Benefix (nonacog alfa) and Idelvion (albutrepenonacog alfa) are indeed recognized brand names for therapeutic products utilizing recombinant Factor IX.
Tranexamic acid is used to directly replace the missing Factor IX in patients with hemophilia B.
Answer: False
Tranexamic acid is an antifibrinolytic agent that aids in clot stabilization. It does not replace Factor IX but can be used adjunctively to reduce bleeding risk in certain situations.
In Australia, Factor IX treatments like Benefix are available over-the-counter without a prescription.
Answer: False
Factor IX replacement therapies, such as Benefix, are prescription-only medications and are not available over-the-counter in Australia or most other jurisdictions.
The primary route of administration for Factor IX treatments like Rixubis is intramuscular injection.
Answer: False
Factor IX replacement therapies, including Rixubis, are administered intravenously (IV) to ensure direct entry into the bloodstream for systemic circulation.
Eftrenonacog alfa (Alprolix) is a formulation of Factor IX that utilizes an Fc fusion protein.
Answer: True
Eftrenonacog alfa (Alprolix) is indeed a Factor IX therapy that incorporates an Fc fusion protein technology to extend its half-life.
Who were the scientists credited with the initial cloning of the F9 gene?
Answer: Kotoku Kurachi and Earl Davie
The pioneering work of cloning the F9 gene was performed by Kotoku Kurachi and Earl Davie in 1982.
What was the significance of the transgenic sheep named Polly?
Answer: It demonstrated the production of human Factor IX in livestock.
The transgenic sheep Polly was genetically engineered to produce human Factor IX, showcasing the potential of using livestock as bioreactors for therapeutic protein production.
Which of the following is a brand name for a recombinant Factor IX treatment mentioned in the source?
Answer: Rixubis
Rixubis is listed as a brand name for a recombinant Factor IX treatment, alongside others like Benefix and Idelvion.
What is the function of tranexamic acid in managing Factor IX deficiency, particularly during surgery?
Answer: It helps stabilize blood clots and reduce bleeding risk.
Tranexamic acid functions as an antifibrinolytic agent, enhancing the stability of blood clots and thereby reducing bleeding risk, particularly in surgical contexts for patients with bleeding disorders.