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From Proteopedia
HUMAN SOS1 PLECKSTRIN HOMOLOGY (PH) DOMAIN, NMR, 20 STRUCTURES
Structural highlights
Disease[SOS1_HUMAN] Defects in SOS1 are the cause of gingival fibromatosis 1 (GGF1) [MIM:135300]; also known as GINGF1. Gingival fibromatosis is a rare overgrowth condition characterized by a benign, slowly progressive, nonhemorrhagic, fibrous enlargement of maxillary and mandibular keratinized gingiva. GGF1 is usually transmitted as an autosomal dominant trait, although sporadic cases are common.[1] Defects in SOS1 are the cause of Noonan syndrome type 4 (NS4) [MIM:610733]. NS4 is an autosomal dominant disorder characterized by dysmorphic facial features, short stature, hypertelorism, cardiac anomalies, deafness, motor delay, and a bleeding diathesis. It is a genetically heterogeneous and relatively common syndrome, with an estimated incidence of 1 in 1000-2500 live births. Rarely, NS4 is associated with juvenile myelomonocytic leukemia (JMML). SOS1 mutations engender a high prevalence of pulmonary valve disease; atrial septal defects are less common.[2] [3] [4] [5] [6] [7] [8] [9] Function[SOS1_HUMAN] Promotes the exchange of Ras-bound GDP by GTP. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA large subset of pleckstrin homology (PH) domains are immediately to the C terminus of diffuse B cell lymphoma (Dbl) homology (DbH) domains. Dbl domains are generally considered to be GTPase-exchange factors; many are proto-oncogenes. PH domains appear to function as membrane-recruitment factors, or have specific protein-protein interactions. Since dual domain (DbH/PH) constructs are known to have significant properties in other pathways, it is possible that a defined interdomain relationship is required for DbH/PH function. We determined the solution structure of the human SOS1 PH domain for a construct partially extended into the preceding DbH domain. There are specific structural contacts between the PH and the vestigial DbH domain. This appears to involve structural elements common to this subfamily of PH domains, and to DbH domains. The human SOS1 PH domain binds to inositol 1,4,5-triphosphate with a approximately 60 mu M affinity. Using chemical shift titration, the binding site is identified to be essentially identical to that observed crystallographically for the inositol 1,4,5-triphosphate complex with the PH domain of phospholipase Cdelta. This site may serve as an interdomain regulator of DbH or other domains' functions. While the overall fold of the human SOS1 PH domain is similar to other PH domains, the size and position of the intrastrand loops and the presence of an N-terminal alpha-helix of the vestigial DbH domain suggest that the subfamily of PH domains associated with DbH domains may be a well defined structural group in which the PH domain is a membrane recruiter and modulator. The solution structure of the pleckstrin homology domain of human SOS1. A possible structural role for the sequential association of diffuse B cell lymphoma and pleckstrin homology domains.,Zheng J, Chen RH, Corblan-Garcia S, Cahill SM, Bar-Sagi D, Cowburn D J Biol Chem. 1997 Nov 28;272(48):30340-4. PMID:9374522[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Human | Cowburn, D | Zheng, J | Signal transduction | So
