background:
BBS9 is an 887 amino acid protein that localizes to both the cytoplasm and the centrosome and exists as six alternatively spliced isoforms. Expressed in a wide variety of tissues, including liver, lung, heart, brain and skeletal muscle, BBS9 functions as a component of the multi-protein BBSome complex which is required for ciliogenesis and is regulated by GDP/GTP exchange factors. Defects in the gene encoding BBS9 are associated with the pathogenesis of Bardet-Biedl syndrome type 9 (BBS9), an autosomal recessive disorder that is characterized by severe pigmentary retinopathy, early onset obesity, polydactyly, hypogenitalism, renal malformation and mental retardation. Additionally, chromosomal aberrations involving the BBS9 gene may play a role in the formation of Wilms tumor 5 (WT5).
Function:
The BBSome complex is required for ciliogenesis but is dispensable for centriolar satellite function. This ciliogenic function is mediated in part by the Rab8 GDP/GTP exchange factor, which localizes to the basal body and contacts the BBSome. Rab8(GTP) enters the primary cilium and promotes extension of the ciliary membrane. Firstly the BBSome associates with the ciliary membrane and binds to RAB3IP/Rabin8, the guanosyl exchange factor (GEF) for Rab8 and then the Rab8-GTP localizes to the cilium and promotes docking and fusion of carrier vesicles to the base of the ciliary membrane.
Subunit:
Part of BBSome complex, that contains BBS1, BBS2, BBS4, BBS5, BBS7, BBS8, BBS9 and BBIP10. The BBSome complex binds to PCM1 and tubulin.
Subcellular Location:
Cytoplasm, cytoskeleton, centrosome. Cell projection, cilium membrane. Cytoplasm. Note=Localizes to nonmembranous centriolar satellites in the cytoplasm.
Tissue Specificity:
Widely expressed. Expressed in adult heart, skeletal muscle, lung, liver, kidney, placenta and brain, and in fetal kidney, lung, liver and brain.
DISEASE:
Defects in BBS9 are a cause of Bardet-Biedl syndrome type 9 (BBS9) [MIM:209900]. Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, autosomal recessive disorder characterized by usually severe pigmentary retinopathy, early onset obesity, polydactyly, hypogenitalism, renal malformation and mental retardation.
Database links:
Entrez Gene: 27241 Human
Entrez Gene: 319845 Mouse
Entrez Gene: 315484 Rat
Omim: 607968 Human
SwissProt: Q3SYG4 Human
SwissProt: Q811G0 Mouse
Unigene: 37272 Human
Unigene: 176725 Mouse
Unigene: 92828 Rat
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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