The TNNI2 antibody targets troponin I type 2 (TNNI2), a protein encoded by the TNNI2 gene located on chromosome 20 in humans. TNNI2 is a fast-twitch skeletal muscle-specific isoform of troponin I, a key regulatory component of the troponin complex in striated muscle. This complex, which also includes troponin T and C, plays a central role in calcium-dependent regulation of muscle contraction. TNNI2 binds to actin in thin filaments, inhibiting actomyosin ATPase activity during muscle relaxation. Its expression is primarily restricted to fast skeletal muscle fibers, distinguishing it from cardiac (TNNI3) and slow skeletal (TNNI1) isoforms.
Mutations in TNNI2 are associated with distal arthrogryposis (DA), a group of congenital disorders characterized by joint contractures and muscle weakness. Research using TNNI2 antibodies has elucidated its role in these pathologies, including impaired calcium sensitivity and disrupted sarcomere function. The antibody is widely employed in techniques like Western blotting, immunohistochemistry, and immunofluorescence to study TNNI2 expression patterns in muscle development, regeneration, and disease models. Recent studies also explore its potential as a biomarker in certain cancers, particularly rhabdomyosarcoma, where aberrant expression may correlate with tumor progression. As a research tool, TNNI2 antibodies contribute to understanding muscle physiology and molecular mechanisms underlying neuromuscular disorders.