Multiple isoforms and an unusual cathodic isoform of creatine kinase from channel catfish (Ictalurus punctatus)

In vertebrates, the creatine kinase (CK) family consists of two cytosolic a nd two mitochondrial isoforms. The two cytosolic, isoforms are the muscle t ype (M-CK) and the brain type (B-CK). Here we report multiple CK isoenzymes in the diploid channel catfish (Ictalurus punctatus) with one unusual cath odic isoform that was previously found only in pathological situations in h uman. The cathodic CK isoform existed only in the channel catfish stomach, ovary, and spleen, but not in any other species analyzed such as tilapia, s mallmouth bass, chicken, or rat. Two genes encode the multiple forms of the channel catfish M-CK cDNAs. M-CK1 has three alleles, M-CK1.1, M-CK1.2, and M-CK1.3, while M-CK2 has just one allele as determined by analysis of 17 c DNA clones and by allele-specific PCR. M-M encodes a protein of 381 amino a cids and the M-CK2 cDNA encodes a protein of 380 amino acids. The two cDNAs shared an 86% identity and both have the nine diagnostic boxes for cytosol ic CKs and thus are of cytosolic origin. The M-CK1 gene was isolated, seque nced, and characterized and its promoter should be useful for transgenic re search for muscle-specific expression. (C) 2001 Elsevier Science B.V. All r ights reserved.