We have localized the gene encoding the fast skeletal muscle
isoform of troponin I (TNNI2) to
11p15.5 by PCR-based analysis of somatic cell hybrid panels: based on the
hybrid panel, TNNI2 is coincident with the marker D11S922. The gene encoding
the fast skeletal
muscle troponin T gene (TNNT3) has been previously assigned to 11p15.5
suggesting that TNNI2
and TNNT3 may be closely linked. The overall location of genes encoding
troponin I and T isoforms
now reveals that they are organized at three loci each containing a
troponin I/troponin T gene pair.
This organization contrasts with all other sarcomeric protein genes and
has implications for the
evolution of these two gene families, for their regulation and for the
analysis of mutations suspected to result in cardiomyopathy.