Sorbin is an active peptide present in the digestive tract, where it has pro-absorptive and anti-secretory effects in different parts of the intestine, including the ability to decrease VIP (vasoactive intestinal peptide) and cholera toxin-induced secretion. It is expressed in some intestinal and pancreatic endocrine tumours in humans [ (PUBMED:10704721) ].
Sorbin-homology (SoHo) domains are found in adaptor proteins such as vinexin, CAP/ponsin and argBP2, which regulate various cellular functions, including cell adhesion, cytoskeletal organisation, and growth factor signalling [ (PUBMED:11937713) ]. In addition to the sorbin domain, these proteins contain three SH3 (src homology 3) domains. The sorbin homology domain mediates the interaction of vinexin and CAP with flotillin, which is crucial for the localisation of SH3-binding proteins to the lipid raft, a region of the plasma membrane rich in cholesterol and sphingolipids that acts to concentrate certain signalling molecules. The sorbin homology domain of adaptor proteins may mediate interactions with the lipid raft that are crucial to intracellular communication [ (PUBMED:11481476) ].
Human sorbin is generated via splicing of an alternative transcript from the ArgBP2 gene locus [ (PUBMED:15949647) ].
Family alignment:
There are 4291 Sorb domains in 4287 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing Sorb domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with Sorb domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing Sorb domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
nArgBP2, a novel neural member of ponsin/ArgBP2/vinexin family that interacts with synapse-associated protein 90/postsynaptic density-95-associated protein (SAPAP).
J Biol Chem. 1999; 274: 30914-8
Display abstract
Postsynaptic density (PSD)-95/synapse-associated protein (SAP) 90 and synaptic scaffolding molecule (S-SCAM) are synaptic membrane-associated guanylate kinases. Both the proteins interact with SAP90/PSD-95-associated protein (SAPAP) (also called guanylate kinase-associated protein/Dlg-associated protein). SAPAP is a protein highly enriched in the PSD fraction and may link PSD-95/SAP90 and S-SCAM to Triton X-100-insoluble structures. We found here a novel SAPAP-interacting protein, which was specifically expressed in neural tissue and was present in the postsynaptic density fraction in brain. This protein had a sorbin homology domain in the N terminus, a zinc finger motif in the middle region, and three src homology (SH) 3 domains in the C terminus and was homologous to the ponsin/ArgBP2/vinexin family proteins. We named this protein nArgBP2 because it was the most homologous to ArgBP2. nArgBP2 is a neural member of a growing family of SH3-containing proteins. nArgBP2 bound to the proline-rich region of SAPAP via its third SH3 domain and was coimmunoprecipitated with SAPAP from the extract of rat brain. Furthermore, nArgBP2 was colocalized with SAPAP at synapses in cerebellum. nArgBP2 bound to not only SAPAP but also vinculin and l-afadin, known to bind to ponsin and vinexin. nArgBP2 may be implicated in the protein network around SAPAP in the PSD.
A role for CAP, a novel, multifunctional Src homology 3 domain-containing protein in formation of actin stress fibers and focal adhesions.
J Biol Chem. 1998; 273: 4073-80
Display abstract
c-Cbl-associated protein, CAP, was originally cloned from a 3T3-L1 adipocyte cDNA expression library using full-length c-Cbl as a bait. CAP contains a unique structure, with three adjacent Src homology-3 (SH3) domains in the COOH terminus and a region sharing significant sequence similarity with the peptide hormone sorbin. Expression of CAP in NIH-3T3 cells overexpressing the insulin receptor induced the formation of stress fibers and focal adhesions. This effect of CAP expression on the organization of the actin-based cytoskeleton was independent of the type of integrin receptors engaged with extracellular matrix, whereas membrane ruffling and decreased actin stress fibers induced by insulin were not affected by expression of CAP. Immunofluorescence microscopy demonstrated that CAP colocalized with actin stress fibers. Moreover, CAP interacted with the focal adhesion kinase, p125FAK, both in vitro and in vivo through one of the SH3 domains of CAP. The increased formation of stress fibers and focal adhesions in CAP-expressing cells was correlated with decreased tyrosine phosphorylation of p125FAK in growing cells or upon integrin-mediated cell adhesion. These results suggest that CAP may mediate signals for the formation of stress fibers and focal adhesions.
Sorbin has been isolated from extracts of porcine upper intestine, and the biological activity in absorbing water and electrolytes utilized to monitor the purification procedure. Pure sorbin was obtained in a yield of about 1 mg/Mg boiled intestine. The protein chain has 153 amino acid residues and the primary structure was determined by analyses of CNBr-cleaved fragments and four enzymatic digests. The protein has a free N-terminal Met and an amidated C-terminal Ala. No structural similarity was observed with other known proteins in data bases, but several segments have special properties and the C-terminal half is rich in Pro and Arg.
Metabolism (metabolic pathways involving proteins which contain this domain)
This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with Sorb domain which could be assigned to a KEGG orthologous group, and not all proteins containing Sorb domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.
Links (links to other resources describing this domain)
