Structure and expression of carp mitogen-activated protein kinases homologous to mammalian JNK/SAPK.

Two distinct stress-activated protein kinase (JNKa and b) cDNAs were isolated from a carp ovary cDNA library. These cDNAs contained a full-length open reading frame encoding 427 amino acid residues with a predicted mass of 48.6 kDa. The deduced amino acid sequences of JNKa and b were 95.8% identical, with 18 residues replaced, and showed a high degree of sequence similarity to mammalian JNK/SAPK subgroup including the common dual phosphorylation motif of TPY. By Northern blot analysis, the carp JNKs were found to be abundant in the brain and ovary. Detailed study by RT-PCR assay revealed ubiquitous expression of JNKb, although expression of JNKa was specific to the brain and ovary. The high level expression of both JNKa and b in the ovary implies that JNKs play an important role in egg maturation or ectogenetic early development.