Molecular cloning of proopiomelanocortin (POMC) cDNA from mud turtle, Pelodiscus sinensis.
The complete complementary DNA (cDNA) of proopiomelanocortin (POMC), a common precursor of opioid hormone beta-endorphin, melanotropin (MSH), and corticortropin (ACTH), was cloned and sequenced from pituitary and hypothalamus of mud turtle (Pelodiscus sinensis) by RT-PCR and rapid amplification of cDNA end (RACE) methods. Two transcripts of POMC mRNAs with different polyadenylation sites were observed. Both transcripts had an open reading frame encoding a 261-amino acid peptide containing nine dibasic amino acids (pair of Arg and Lys), putative proteolytic cleavage sites for processing to functional peptides. All the functional peptide fragments of mud turtle POMC, gamma-MSH, alpha-MSH, ACTH, beta-MSH, and beta-endorphin, are flanked by dibasic residues as found in other tetrapods, implying that it could be processed to give rise to all members of POMC-derived peptides. The deduced amino acid sequences of mud turtle POMC displays 63-67% identity with amphibian, 59% with chicken, 48-53% with mammals, and 37-59% identity with fish. However, functional peptide fragments are much more conserved than overall sequence and intervening fragments. In addition to pituitary and brain, mud turtle POMC mRNAs are also expressed in many peripheral tissues, such as skin, thyroid, and testis. This is the first report on the complete sequence of cDNA nucleotides and deduced amino acids of POMC in reptile.
Shen
San-Tai
ST
Endocrinology Laboratory, Institute of Zoology, Academia Sinica, Taipei 115, Taiwan, ROC.
Lu
Li-Ming
LM
Chen
Jia-Ru
JR
Chien
Jung-Tsun
JT
Yu
John Yuh-Lin
JY
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002540:Cerebral Cortex / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics* / Q000302:isolation & purification*; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA; D012867:Skin / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D013961:Thyroid Gland / Q000378:metabolism; D014018:Tissue Distribution; D014426:Turtles / Q000235:genetics*
D018076:DNA, Complementary; D012333:RNA, Messenger; D011333:Pro-Opiomelanocortin