STRUCTURE CHARACTERISTICS OF MELANIN-CONCENTRATING HORMONE 1 GENE AND ITS PROTEIN FROM MISGURNUS ANGUILLICAUDATUS

Melanin-concentrating hormone (MCH) played an important role in the process of skin melanin pigmentation. In order to known its characteristics and founction, the cDNA sequence of the MCH (refers to MaPmch1) from loach of the Poyang Lake was first cloned by RACE-PCR. Bioinformatics approaches were used to analyze physicochemical property, conserved domains, secondary structures, homologous analysis and phylogenetic tree. The full length of MaPmch1 gene was 570 bp that contained an open reading frame of 375 bp encoding 124 amino acid residues. A CpG island with the length of 110 bp in the cDNA sequence of MaPmch1was located in 263-372 bp. It was predicted that the MaPMCH1 contained seven potential phosphorylation sites. A 17-AA-amidated cyclic neuropeptide named MaMCH1 was generated from MaPMCH1 after hydrolyzing. MaPMCH1 and MaMCH1 were predicted to be hydrophilic proteins mainly contained random coil for their secondary structures. The super secondary structure of MaMCH1 with anantiparallel β-plated sheet, was connected by a disulfide bond. Homology analysis indicated that the amino acid sequence of MaMCH1 was highly conserved with other bony fishes. The phylogenetic tree showed that MaPMCH1 and Cyprinid fish's PMCH1 were in the same branch, and the genetic relationship of PMCH1 was conserved with the traditional classification status. In vertebrate, RCM^*GRVYRPCW (^* as random amino acid) was a highly conserved sequence, suggesting that Pmch1 gene was highly conserved during the evolution.