Ja. Heinig et al., THE APPEARANCE OF PROOPIOMELANOCORTIN EARLY IN VERTEBRATE EVOLUTION -CLONING AND SEQUENCING OF POMC FROM A LAMPREY PITUITARY CDNA LIBRARY, General and comparative endocrinology, 99(2), 1995, pp. 137-144
A proopiomelanocortin (POMC)-like hormone has been cloned and sequence
d from a pituitary cDNA library of upstream migrant (prespawning) sea
lamprey, Petromyzon marinus. The clone, designated LPP-1, consisted of
986 nucleotides, with an open reading frame of 277 amino acids, inclu
ding a signal peptide of 22 amino acids. Like POMCs from more recently
evolved vertebrates, lamprey POMC contained domains which corresponde
d to alpha-MSH, ACTH, and beta-endorphin. However, sequences correspon
ding to gamma- and beta-MSH are absent or likely nonfunctional, respec
tively, in this cDNA. Northern blot analyses showed low but detectable
expression levels of LPP-1 in larvae and strong expression in parasit
ic adults and prespawning animals. These observations indicate that a
recognizable POMC, distinct from proenkephalin, has an ancient lineage
within subphylum Vertebrata, likely dating back to the last common an
cestor of the lamprey and gnathostome lines. (C) 1995 Academic Press,
Inc.