OBSCN

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.

obscurin, cytoskeletal calmodulin and titin-interacting RhoGEF

Structural component of striated muscles which plays a role in myofibrillogenesis. Probably involved in the assembly of myosin into sarcomeric A bands in striated muscle (PubMed:11448995, PubMed:16205939).
Has serine/threonine protein kinase activity and phosphorylates N-cadherin CDH2 and sodium/potassium-transporting ATPase subunit ATP1B1 (By similarity).
Binds (via the PH domain) strongly to phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2) and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), and to a lesser extent to phosphatidylinositol 3-phosphate (PtdIns3P), phosphatidylinositol 4-phosphate (PtdIns4P), phosphatidylinositol 5-phosphate (PtdIns5P) and phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) (PubMed:28826662).

Cell-cell adhesionManual Assertion Based On ExperimentIBA:GO_Central
Protein localization to M-bandBy SimilarityISS:BHF-UCL
Regulation of small GTPase mediated signal transductionTAS:Reactome
Sarcomere organizationManual Assertion Based On ExperimentTAS:BHF-UCL

Isoform 3
Cytoplasm, myofibril, sarcomere, M line
Cytoplasm, myofibril, sarcomere, Z line
In differentiating skeletal muscle cells, isoform 3 primarily localizes to the sarcomeric M-line and less frequently to the Z-disk (PubMed:12527750).
Isoform 3 colocalizes with ANK1 isoform Mu17/ank1.5 at the M-line in differentiated skeletal muscle cells (PubMed:12527750).
Cytoplasm, myofibril, sarcomere, M line
Cytoplasm, myofibril, sarcomere, Z line
Cell membrane, sarcolemma
Nucleus
Colocalizes with CDH2 and ATP1B1 to the sarcolemma and to intercalating disks in cardiac muscles. Colocalizes with ATP1B1 to M line and Z line in cardiac muscles.

A chromosomal aberration involving OBSCN has been found in Wilms tumor. Translocation t(1;7)(q42;p15) with PTHB1.

Autophosphorylated by protein kinase domains 1 and 2.