Tpm1^tm1Dfw

The striated muscle-specific exons 12 and 13 were replaced with an HPRT cassette in the reverse orientation. While the targeting construct was designed to knock-out the striated muscle isoform, the targeted allele is null. Interestingly, heterozygotes exhibit normal protein levels, despite a ~50% reduction in mRNA levels and absence of compensation by the striated muscle beta or the slow skeletal alpha isoforms, suggesting that a compensatory mechanism may operate at the translational level. (J:45833)