Two distinct cDNAs encoding troponin C (TnC) isoforms were isolated fr
om the ascidian, Halocynthia roretzi, One is expressed in adult body w
all smooth muscle and heart muscle, and the other in larval striated m
uscle, The H. rorezti gene is composed of 7 exons separated by B intro
ns, and Southern blot analysis showed that TnC is a single copy gene p
roduct. The two isoforms of TnC were derived through the alternative s
plicing of the third exon.