GP1BB gene

glycoprotein Ib platelet beta subunit

The GP1BB gene provides instructions for making a protein called glycoprotein 1b-beta (GPIbβ). This protein is one piece (subunit) of a protein complex called GPIb-IX-V, which plays a role in blood clotting. GPIb-IX-V is found on the surface of small cell fragments called platelets, which circulate in blood and are an essential component of blood clots. The complex can attach (bind) to a protein called von Willebrand factor, fitting together like a lock and its key. Von Willebrand factor is found on the inside surface of blood vessels, particularly when there is an injury. Binding of the GPIb-IX-V complex to von Willebrand factor allows platelets to stick to the blood vessel wall at the site of the injury. These platelets form clots, plugging holes in the blood vessels to help stop bleeding.

To form the GPIb-IX-V complex, GPIbβ interacts with other protein subunits called GPIb-alpha, GPIX, and GPV, each of which is produced from a different gene. GPIbβ is essential for assembly of the complex at the platelet surface and helps stabilize the complex once it is formed.

At least 32 GP1BB gene mutations have been found to cause Bernard-Soulier syndrome, a condition characterized by a reduced number of platelets that are larger than normal (macrothrombocytopenia) and excessive bleeding. These mutations lead to production of an altered GPIbβ subunit that is likely broken down too soon or that cannot get to the platelet surface. Lack of this subunit on the surface of platelets prevents formation of the GPIb-IX-V complex. Without GPIb-IX-V, platelets cannot come together at the site of an injury to form a clot, leading to the bleeding problems associated with Bernard-Soulier syndrome.

Cytogenetic Location: 22q11.21, which is the long (q) arm of chromosome 22 at position 11.21

Molecular Location: base pairs 19,723,543 to 19,724,774 on chromosome 22 (Homo sapiens Annotation Release 108, GRCh38.p7) (NCBI)

Cytogenetic Location: 22q11.21, which is the long (q) arm of chromosome 22 at position 11.21
  • antigen CD42b-beta
  • BDPLT1
  • BS
  • CD42C
  • glycoprotein Ib (platelet), beta polypeptide
  • GP-Ib beta
  • GPIbbeta
  • nuclear localization signal deleted in velocardiofacial syndrome
  • platelet glycoprotein Ib beta chain precursor
  • platelet membrane glycoprotein Ib beta
  • truncated platelet membrane glycoprotein Ib beta