BBS4: May be required for the dynein-mediated transport of pericentriolar proteins to the centrosome. Required for microtubule anchoring at the centrosome but not for microtubule nucleation. 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. Defects in BBS4 are the cause of Bardet-Biedl syndrome type 4 (BBS4). 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. Secondary features include diabetes mellitus, hypertension and congenital heart disease. A relatively high incidence of BBS is found in the mixed Arab populations of Kuwait and in Bedouin tribes throughout the Middle East, most likely due to the high rate of consaguinity in these populations and a founder effect. Belongs to the BBS4 family. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: Cell development/differentiation; Adaptor/scaffold; Microtubule-binding
Chromosomal Location of Human Ortholog: 15q22.3-q23
Cellular Component: centriole; centrosome; pericentriolar material; nonmotile primary cilium; cytosol; cilium
Molecular Function: protein binding; beta-tubulin binding; microtubule motor activity; alpha-tubulin binding
Biological Process: fat cell differentiation; retinal rod cell development; regulation of lipid metabolic process; metabolic process; photoreceptor cell maintenance; positive regulation of multicellular organism growth; retinal homeostasis; protein transport; sensory processing; intracellular transport; visual perception; cytokinesis after mitosis; sensory cilium biogenesis; centrosome organization and biogenesis; dendrite development; brain morphogenesis; cilium biogenesis; heart looping; maintenance of protein localization in nucleus; positive regulation of flagellum biogenesis; striatum development; negative regulation of systemic arterial blood pressure; organelle organization and biogenesis; hippocampus development; sensory perception of smell; microtubule cytoskeleton organization and biogenesis; regulation of cytokinesis; melanosome transport; protein localization in organelle; adult behavior; neural tube closure; cerebral cortex development; spermatid development
Disease: Bardet-biedl Syndrome 4; Bardet-biedl Syndrome 1
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