Myotrophin (MTPN)

Myotrophin, a 12-kD protein, was originally isolated by Sen et al. (1990) from the hypertrophied ventricles of spontaneously hypertensive rats and later by Sil et al. (1993) from dilated cardiomyopathic human hearts. Mukherjee et al. (1993) found that myotrophin increases the transcript levels of protooncogenes as well as the transcript levels of beta-myosin heavy chain and ANF, markers for cardiac hypertrophy.The 117-amino acid protein contained an acetylated N terminus and 2.5 internal 33-amino acid ankyrin repeats. Sivasubramanian et al. (1996) identified a second half-ankyrin repeat in rat Mtpn. Northern blot analysis detected up to 7 transcripts between 0.4 and 4.3 kb expressed in all rat tissues examined. Highest levels were detected in brain, and lowest levels in skeletal muscle.