SH3 domain

SH3 domain

Ribbon diagram of the SH3 domain, alpha spectrin, from chicken (PDB accession code 1SHG), colored from blue (N-terminus) to red (C-terminus).
Identifiers
Symbol SH3_1
Pfam PF00018
Pfam clan CL0010
InterPro IPR001452
SMART SM00326
PROSITE PS50002
SCOP 1shf
SUPERFAMILY 1shf
CDD cd00174

The SRC Homology 3 Domain (or SH3 domain) is a small protein domain of about 60 amino acid residues. Initially, SH3 was described as a conserved sequence in the viral adaptor protein v-Crk. This domain is also present in the molecules of phospholipase and several cytoplasmic tyrosine kinases such as Abl and Src.[1][2] It has also been identified in several other protein families such as: PI3 Kinase, Ras GTPase-activating protein, CDC24 and cdc25.[3][4][5] SH3 domains are found in proteins of signaling pathways regulating the cytoskeleton, the Ras protein, and the Src kinase and many others. The SH3 proteins interact with adaptor proteins and tyrosine kinases. Interacting with tyrosine kinases SH3 proteins usually bind far away from the active site. Approximately 300 SH3 domains are found in proteins encoded in the human genome.

Structure

The SH3 domain has a characteristic beta-barrel fold that consists of five or six β-strands arranged as two tightly packed anti-parallel β sheets. The linker regions may contain short helices. The SH3-type fold is an ancient fold found in eukaryotes as well as prokaryotes.[6]

Peptide binding

The classical SH3 domain is usually found in proteins that interact with other proteins and mediate assembly of specific protein complexes, typically via binding to proline-rich peptides in their respective binding partner. Classical SH3 domains are restricted in humans to intracellular proteins, although the small human MIA family of extracellular proteins also contain a domain with an SH3-like fold.

Many SH3-binding epitopes of proteins have a consensus sequence that can be represented as a regular expression or Short linear motif:

-X-P-p-X-P-
 1 2 3 4 5

with 1 and 4 being aliphatic amino acids, 2 and 5 always and 3 sometimes being proline. The sequence binds to the hydrophobic pocket of the SH3 domain. More recently, SH3 domains that bind to a core consensus motif R-x-x-K have been described. Examples are the C-terminal SH3 domains of adaptor proteins like Grb2 and Mona (a.k.a. Gads, Grap2, Grf40, GrpL etc.). Other SH3 binding motifs have emerged and are still emerging in the course of various molecular studies, highlighting the versatility of this domain.

Proteins with SH3 domain

See also

References

  1. ↑ Pawson T, Schlessingert J (July 1993). "SH2 and SH3 domains". Curr. Biol. 3 (7): 434–42. doi:10.1016/0960-9822(93)90350-W. PMID 15335710.
  2. ↑ Mayer BJ (April 2001). "SH3 domains: complexity in moderation". J. Cell. Sci. 114 (Pt 7): 1253–63. PMID 11256992.
  3. ↑ Musacchio A, Gibson T, Lehto VP, Saraste M (July 1992). "SH3--an abundant protein domain in search of a function". FEBS Lett. 307 (1): 55–61. doi:10.1016/0014-5793(92)80901-R. PMID 1639195.
  4. ↑ Mayer BJ, Baltimore D (January 1993). "Signalling through SH2 and SH3 domains". Trends Cell Biol. 3 (1): 8–13. doi:10.1016/0962-8924(93)90194-6. PMID 14731533.
  5. ↑ Pawson T (February 1995). "Protein modules and signalling networks". Nature. 373 (6515): 573–80. doi:10.1038/373573a0. PMID 7531822.
  6. ↑ Whisstock JC, Lesk AM (April 1999). "SH3 domains in prokaryotes". Trends Biochem. Sci. 24 (4): 132–3. doi:10.1016/s0968-0004(99)01366-3. PMID 10322416.
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