Gene: GP1BB

Alternate names for this Gene: BDPLT1|BS|CD42C|GPIBB|GPIbbeta

Gene Summary: Platelet glycoprotein Ib (GPIb) is a heterodimeric transmembrane protein consisting of a disulfide-linked 140 kD alpha chain and 22 kD beta chain. It is part of the GPIb-V-IX system that constitutes the receptor for von Willebrand factor (VWF), and mediates platelet adhesion in the arterial circulation. GPIb alpha chain provides the VWF binding site, and GPIb beta contributes to surface expression of the receptor and participates in transmembrane signaling through phosphorylation of its intracellular domain. Mutations in the GPIb beta subunit have been associated with Bernard-Soulier syndrome, velocardiofacial syndrome and giant platelet disorder. The 206 amino acid precursor of GPIb beta is synthesized from a 1.0 kb mRNA expressed in plateletes and megakaryocytes. A 411 amino acid protein arising from a longer, unspliced transcript in endothelial cells has been described; however, the authenticity of this product has been questioned. Yet another less abundant GPIb beta mRNA species of 3.5 kb, expressed in nonhematopoietic tissues such as endothelium, brain and heart, was shown to result from inefficient usage of a non-consensus polyA signal in the neighboring upstream gene (SEPT5, septin 5). In the absence of polyadenylation from its own imperfect site, the SEPT5 gene produces read-through transcripts that use the consensus polyA signal of this gene.

Gene is located in Chromosome: 22

Location in Chromosome : 22q11.21

Description of this Gene: glycoprotein Ib platelet subunit beta

Type of Gene: protein-coding

Gene: SEPT5-GP1BB

Alternate names for this Gene: GP1BB|GPIb-beta|GPIbB

Gene Summary: This locus represents naturally occurring read-through transcription between the neighboring SEPT5 (septin 5) and GP1BB (glycoprotein Ib (platelet), beta polypeptide) genes on chromosome 22. This read-through transcription arises from inefficient use of an imperfect polyA signal in the upstream SEPT5 gene, whereby transcription continues into the GP1BB gene. Alternative splicing results in multiple read-through variants. The read-through transcripts are candidates for nonsense-mediated mRNA decay (NMD), and are therefore unlikely to produce protein products.

Gene is located in Chromosome: 22

Location in Chromosome : 22q11.21

Description of this Gene: SEPT5-GP1BB readthrough

Type of Gene: ncRNA

rs121909751 in GP1BB;SEPT5-GP1BB gene and Bernard-Soulier Syndrome PMID 9116284 1997 Missense mutations of the glycoprotein (GP) Ib beta gene impairing the GPIb alpha/beta disulfide linkage in a family with giant platelet disorder.