The troponin (Tn) complex regulates calcium-induced muscle contraction. Tn contains three subunits, Ca2+ binding (TnC), inhibitory (TnI), and tropomyosin binding (TnT), which is required for Ca(2+)-mediated activation of actomyosin ATPase activity [, ]. Three different troponin T genes that encode tissue-specific isoforms of subunit T have been found in mammals and birds, encoding cardiac (TNNT2), slow (TNNT1), and fast (TNNT3) skeletal muscle TnT isoforms [, , , ].Mutations of the TNNT1gene cause nemaline myopathy [], while mutations of the TNNT2 gene cause familial hypertrophic cardiomyopathy [, ], and mutations of the TNNT3 gene cause Arthrogryposis, distal, 2B2 (DA2B2) [].
