FIGURE 4.
Cloning of cDNAs encoding ssTnT from toad cardiac mRNA. A, two degenerated primers derived from amino acid sequences conserved in vertebrate ssTnT were used in RT-PCR to clone ssTnT cDNA from total RNA extracted from adult toad cardiac muscle. Extended using 3′- and 5′-rapid amplification of cDNA ends, two full-length ssTnT cDNA variants were cloned. DNA sequencing revealed their difference in the inclusion or exclusion of the exon 5-encoded segment (DYGEHIEE) in the NH2-terminal variable region. B, mAb CT3 Western blots showed that ssTnT proteins expressed from the cloned cDNAs had identical apparent molecular weights (MW) to that of the ssTnT bands in toad cardiac and skeletal muscles. The low Mr ssTnT is the only variant detectable with Western blot in the toad cardiac muscle.