Son of sevenless

Function

Son of sevenless or Ras-specific nucleotide exchange factor SOS or son of sevenless homolog or son of sevenless protein homolog (SOS) is a Ras activator in signalling pathways. In mammals SOS is involved in coupling signals originated by cell surface receptor tyrosine kinases to Ras-dependent mitogenic signalling pathways^[1]. SOS is a multi-domain protein whose catalytic domain (homologous to Cdc25 see Dual specificity phosphatase) is active towards Ras and its Dbl holology and pleckstrin homology domains are active in stimulating GTP/GDP exchage.

Disease

Mutations in SOS1 have been reported in Noonan syndrome and in type 1 hereditary gingival fibromatosis^[2].

Relevance

Structural highlights

SOS1 domain structure contains histone domain (HD) residues 1-191, Dbl homology domain (DH) 203-389, pleckstrin homology domain (PH) 443-548, Ras exchange motif (REM) 601-648, catalytic domain 782-1020 and proline-rich region (PR) 1146-1297.