Obscurin is a protein that in humans is encoded by the OBSCN gene.

The obscurin gene spans more than 150 kb, contains over 80 exons and encodes a protein of approximately 720 kDa. The encoded protein contains 68 Ig domains, 2 fibronectin domains, 1 calcium/calmodulin-binding domain, 1 RhoGEF domain with an associated PH domain, and 2 serine-threonine kinase domains. This protein belongs to the family of giant sacromeric signaling proteins that includes titin and nebulin, and may have a role in the organization of myofibrils during assembly and may mediate interactions between the sarcoplasmic reticulum and myofibrils. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008].
Function: Involved in myofibrillogenesis. Seems to be involved in assembly of myosin into sarcomeric A bands in striated muscle. Isoform 3 together with ANK1 isoform Mu17/Ank1.5 may provide a molecular link between the sarcoplasmic reticulum and myofibrils.