Obscurin, SH3 domain (IPR035526)

Short name: Obscurin_SH3

Overlapping homologous superfamilies

Domain relationships

  • SH3 domain (IPR001452)
    • Obscurin, SH3 domain (IPR035526)


Obscurin is a giant muscle protein that is concentrated at the peripheries of Z-disks and M-lines [PMID: 16625317]. It binds small ankyrin I, a component of the sarcoplasmic reticulum (SR) membrane [PMID: 21333652]. It is associated with the contractile apparatus through binding with titin and sarcomeric myosin [PMID: 20133654]. It plays important roles in the organization and assembly of the myofibril and the SR. Obscurin has been observed as alternatively-spliced isoforms. The major isoform in skeletal muscle, approximately 800 kDa in size, is composed of many adhesion modules and signaling domains [PMID: 17382936].

Obscurin harbors 49 Ig and 2 FNIII repeats at the N terminus, a complex middle region with additional Ig domains, an IQ motif, and a conserved SH3 domain near RhoGEF and PH domains, and a non-modular C terminus with phosphorylation motifs. The obscurin gene also encodes two kinase domains, which are not part of the 800 kDa form of the protein, but is part of smaller spliced products present in heart muscle.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.