Troponin I Skeletal Muscle (skTnI) Protein

This gene encodes a fast-twitch skeletal muscle protein, a member of the troponin I gene family, and a component of the troponin complex including troponin T, troponin C and troponin I subunits. The troponin complex, along with tropomyosin, is responsible for the calcium-dependent regulation of striated muscle contraction. Mouse studies show that this component is also present in vascular smooth muscle and may play a role in regulation of smooth muscle function. In addition to muscle tissues, this protein is found in corneal epithelium, cartilage where it is an inhibitor of angiogenesis to inhibit tumor growth and metastasis, and mammary gland where it functions as a co-activator of estrogen receptor-related receptor alpha. This protein also suppresses tumor growth in human ovarian carcinoma. Mutations in this gene cause myopathy and distal arthrogryposis type 2B. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Mar 2009]

TNNI2: Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity. Defects in TNNI2 are a cause of distal arthrogryposis type 2B (DA2B); also known as arthrogryposis multiplex congenita, distal, type 2B (AMCD2B). DA2B is a form of inherited multiple congenital contractures. Affected individuals have vertical talus, ulnar deviation in the hands, severe camptodactyly, and a distinctive face characterized by a triangular shape, prominent nasolabial folds, small mouth and a prominent chin. Belongs to the troponin I family.

Protein type: Motility/polarity/chemotaxis

Chromosomal Location of Human Ortholog: 11p15.5

Cellular Component: troponin complex; cytosol; nucleus

Molecular Function: troponin T binding; protein binding; actin binding

Biological Process: skeletal muscle contraction; regulation of muscle contraction; positive regulation of transcription, DNA-dependent; muscle filament sliding

Disease: Arthrogryposis, Distal, Type 2b