Glycoprotein Ib (GPIb), also known as CD42, is a component of the GPIb-V-IX complex on

platelets Platelets or thrombocytes () are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cyto ...

. The GPIb-V-IX complex binds

von Willebrand factor Von Willebrand factor (VWF) () is a blood glycoprotein that promotes primary hemostasis, specifically, platelet adhesion. It is deficient and/or defective in von Willebrand disease and is involved in many other diseases, including thrombotic thro ...

, allowing

platelet adhesion Platelets or thrombocytes () are a part of blood whose function (along with the coagulation#Coagulation factors, coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a thrombus, blood clot. Platelets have no ...

and

platelet plug The platelet plug, also known as the hemostatic plug or platelet thrombus, is an aggregation of platelets formed during early stages of hemostasis in response to one or more injuries to blood vessel walls. After platelets are recruited and begin ...

formation at sites of vascular injury. Glycoprotein Ibα (GPIbα) is the major ligand-binding subunit of the GPIb-V-IX complex. GPIbα is heavily glycosylated. It is deficient in the

Bernard–Soulier syndrome Bernard–Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder that is caused by a deficiency of the '' glycoprotein Ib-IX-V complex'' (GPIb-IX-V), the receptor for von Willebrand factor. The incidence of BSS is estimated to be ...

. A

gain-of-function mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosi ...

causes platelet-type

von Willebrand disease Von Willebrand disease (VWD) is the most common heredity, hereditary coagulopathy, blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of ...

. Autoantibodies against Ib/IX can be produced in

immune thrombocytopenic purpura Immune thrombocytopenic purpura (ITP), also known as idiopathic thrombocytopenic purpura or immune thrombocytopenia, is an autoimmune primary disorder of hemostasis characterized by a low platelet count in the absence of other causes. ITP often ...

. Components include

GP1BA Platelet glycoprotein Ib alpha chain, also known as glycoprotein Ib (platelet), alpha polypeptide or CD42b (Cluster of Differentiation 42b), is a protein that in humans is encoded by the ''GP1BA'' gene. Function Glycoprotein Ib (GP Ib) is a ...

and

GP1BB Glycoprotein Ib (platelet), beta polypeptide (GP1BB) also known as CD42c (Cluster of Differentiation 42c), is a protein that in humans is encoded by the GP1BB gene. Function Platelet glycoprotein Ib (GPIb) is a heterodimeric transmembrane prot ...

. It complexes with Glycoprotein IX.

References

External links

* Glycoproteins {{protein-stub