CLONING THE PARTIAL CDNAS OF MU-CALPAIN AND M-CALPAIN FROM PORCINE SKELETAL-MUSCLE

Calpains are non-lysosomal proteases involved in myofibrillar protein degradation. To facilitate studying the expression of the porcine calp ain genes and their influence on protein accretion, we have cloned par tial cDNAs for mu- and m-calpain from porcine skeletal muscle via PCR amplification. A 289 bp fragment for mu-calpain and a 629 bp fragment for m-calpain were cloned into the EcoRV site of pBluescript II KS+ ve ctor. The nucleotide sequence for porcine mu-calpain and m-calpain wer e 92% and 90% identical to corresponding regions of rabbit mu- and m-c alpain, respectively. The deduced amino acid sequences for both mu- an d m-calpain share 94% identity with respective rabbit mu- and m-calpai ns. Isoform specificity was validated by Southern hybridization of mu- and m-calpain probes with cloned mu- and m-calpain fragments and Nort hern hybridization with pig muscle mRNA. These clones will be used to evaluate the role of calpain expression in muscle hypertrophy.