Son of sevenless homolog 1 is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

that in humans is encoded by the ''SOS1''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

Function

SOS1 is a

guanine nucleotide exchange factor Guanine nucleotide exchange factors (GEFs) are proteins or protein domains that activate monomeric GTPases by stimulating the release of guanosine diphosphate (GDP) to allow binding of guanosine triphosphate (GTP). A variety of unrelated structu ...

(GEF) which interacts with

Ras proteins Ras, from "Rat sarcoma virus", is a family of related proteins that are expressed in all animal cell lineages and organs. All Ras protein family members belong to a class of protein called small GTPase, and are involved in transmitting signal ...

to phosphorylate GDP into GTP, or from an inactive state to an active state to signal cell proliferation. RAS genes (e.g., MIM 190020) encode membrane-bound guanine nucleotide-binding proteins that function in the transduction of signals that control cell growth and differentiation. Binding of GTP activates RAS proteins, and subsequent hydrolysis of the bound GTP to GDP and phosphate inactivates signaling by these proteins. GTP binding can be catalyzed by

s for RAS, and GTP hydrolysis can be accelerated by

GTPase-activating proteins GTPase-activating proteins or GTPase-accelerating proteins (GAPs) are a family of regulatory proteins whose members can bind to activated G proteins and stimulate their GTPase activity, with the result of terminating the signaling event. GAPs are a ...

(GAPs). The first exchange factor to be identified for RAS was the ''S. cerevisiae'' Cdc25 gene product (not to be confused with the ''S. pombe''

Cdc25 Cdc25 is a dual-specificity phosphatase first isolated from the yeast ''Schizosaccharomyces pombe'' as a cell cycle defective mutant. As with other cell cycle proteins or genes such as Cdc2 and Cdc4, the "cdc" in its name refers to "cell divis ...

). Genetic analysis indicated that CDC25 is essential for activation of RAS proteins. In ''

Drosophila ''Drosophila'' (), from Ancient Greek δρόσος (''drósos''), meaning "dew", and φίλος (''phílos''), meaning "loving", is a genus of fly, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or p ...

'', the protein encoded by the 'son of sevenless' gene (Sos) contains a domain that shows sequence similarity with the catalytic domain of Cdc25. Sos may act as a positive regulator of RAS by promoting guanine nucleotide exchange.

Clinical significance

Recent studies also show that mutations in Sos1 can cause

Noonan syndrome Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored ...

and hereditary gingival fibromatosis type 1. Noonan syndrome has also been shown to be caused by mutations in

KRAS ''KRAS'' ( Kirsten rat sarcoma virus) is a gene that provides instructions for making a protein called K-Ras, a part of the RAS/MAPK pathway. The protein relays signals from outside the cell to the cell's nucleus. These signals instruct the ce ...

and

PTPN11 Tyrosine-protein phosphatase non-receptor type 11 (PTPN11) also known as protein-tyrosine phosphatase 1D (PTP-1D), Src homology region 2 domain-containing phosphatase-2 (SHP-2), or protein-tyrosine phosphatase 2C (PTP-2C) is an enzyme that in hu ...

genes. activators of the MAP kinase pathway.

Inhibitors and activators

In 2019, the first SOS1 inhibitor, BAY-293, was published which met the quality criteria for a 'Donated Chemical Probe' as defined by the

Structural Genomics Consortium The Structural Genomics Consortium (SGC) is a public-private-partnership focusing on elucidating the functions and disease relevance of all proteins encoded by the human genome, with an emphasis on those that are relatively understudied. The SGC pl ...

. Shortly after, the discovery of BI-3406 was published. In 2018, Fesik et al. reported the discovery of benzimidazole-derived SOS1 activators (e.g. VUBI1).

Interactions

SOS1 has been shown to

interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization advocating for the legal and human rights of children with intersex traits. The organization was founded in 2006 and fo ...

with: *

ABI1 Abl interactor 1 also known as Abelson interactor 1 (Abi-1) is a protein that in humans is encoded by the ''ABI1'' gene. Function Abl interactor 1 has been found to form a complex with EPS8 and SOS1, and is thought to be involved in the tra ...

, *

BCR gene The breakpoint cluster region protein (BCR) also known as renal carcinoma antigen NY-REN-26 is a protein that in humans is encoded by the ''BCR'' gene. ''BCR'' is one of the two genes in the ''BCR-ABL'' fusion protein, which is associated with th ...

, * CRK, *

EPS8 Epidermal growth factor receptor kinase substrate 8 is an enzyme that in humans is encoded by the ''EPS8'' gene. Function This gene encodes a member of the EPS8 family. This protein contains one PH domain and one SH3 domain. It functions as pa ...

, *

Epidermal growth factor receptor The epidermal growth factor receptor (EGFR; ErbB-1; HER1 in humans) is a transmembrane protein that is a receptor (biochemistry), receptor for members of the epidermal growth factor family (EGF family) of extracellular protein ligand (biochemistry ...

, *

FRS2 Fibroblast growth factor receptor substrate 2 is a protein that in humans is encoded by the ''FRS2'' gene. FRS2 is an 80 kDa membrane-anchored signal transducing adaptor protein (STAP) that links specific activated Receptor Tyrosine Kinases (RTKs ...

, *

Grb2 Growth factor receptor-bound protein 2, also known as Grb2, is an adaptor protein involved in signal transduction/ cell communication. In humans, the GRB2 protein is encoded by the ''GRB2'' gene. The protein encoded by this gene binds recepto ...

, *

HRAS GTPase HRas, from "Harvey Rat sarcoma virus", also known as transforming protein p21 is an enzyme that in humans is encoded by the gene. The ''HRAS'' gene is located on the short (p) arm of chromosome 11 (human), chromosome 11 at position 15.5, ...

, *

ITSN1 Intersectin-1 is a protein that, in humans, is encoded by the ''ITSN1'' gene. Function The protein encoded by this gene is a cytoplasmic membrane-associated protein that indirectly coordinates endocytic membrane traffic with the actin assembly ...

, *

MUC1 Mucin short variant S1, also called polymorphic epithelial mucin (PEM) or epithelial membrane antigen (EMA), is a mucin encoded by the ''MUC1'' gene in humans. Mucin short variant S1 is a glycoprotein with extensive O-linked glycosylation of its ...

, *

NCK1 Cytoplasmic protein NCK1 is a protein that in humans is encoded by the ''NCK1'' gene. Gene The Nck (non-catalytic region of tyrosine kinase adaptor protein 1) belongs to the adaptor family of proteins. The nck gene was initially isolated fro ...

, * PLCG1, *

, *

SH3KBP1 SH3 domain-containing kinase-binding protein 1 (synonyms - CIN85, in rodents - Ruk) is an adaptor protein that in humans is encoded by the ''SH3KBP1'' gene. Function CBL (MIM 165360) constitutively interacts with SH3 domain-containing prote ...

, and *

SHC1 SHC-transforming protein 1 is a protein that in humans is encoded by the ''SHC1'' gene. SHC has been found to be important in the regulation of apoptosis and drug resistance in mammalian cells. SCOP A ( or ) was a poet as represented in Old ...

. and

References

External links

GeneReviews/NCBI/NIH/UW entry on Noonan syndrome
* http://www.noonansyndrome.org * http://ghr.nlm.nih.gov/gene=sos1 {{NLM content GTP-binding protein regulators