LOCALIZATION OF THE FAST SKELETAL-MUSCLE TROPONIN-I GENE (TNNI2) TO 11PL5.5 - GENES FOR TROPONIN-I AND TROPONIN-T ARE ORGANIZED IN PAIRS

We have localized the gene encoding the fast skeletal muscle isoform o f troponin I (TNNI2) to 11p15.5 by PCR-based analysis of somatic cell hybrid panels: based on the Genebridge4 radiation hybrid panel, TNNI2 is coincident with the marker D119S922. The gene encoding the fast ske letal muscle troponin T gene (TNNT3) has been previously assigned to 1 1p15.5 suggesting that TNNI2 and TNNT3 may be closely linked. The over all location of genes encoding troponin I and T isoforms now reveals t hat they are organized at three loci each containing a troponin I/trop onin T gene pair. This organization contrasts with all other sarcomeri c protein genes and has implications for the evolution of these two ge ne families, for their regulation and for the analysis of mutations su spected to result in cardiomyopathy.