title: Identification and tissue-specific expression of a promethin-like homolog in amphioxus Branchiostoma belcheri.
abstract: Promethins have been shown to be present in the vertebrates examined so far, yet little is known to date about them in invertebrates. Here we isolated a cDNA encoding a promethin-like homolog from the gut cDNA library of the amphioxus Branchiostoma belcheri, a cephalochordate occupying a nodal position transient from invertebrates to vertebrates. It contained a 504 bp open reading frame corresponding to a protein of 167 amino acids. Primary structural examination showed that the deduced promethin-like homolog was a transmembrane protein with three potential transmembrane helices, resembling the vertebrate promethins. Phylogenetic analysis showed that B. belcheri promethin-like homolog was located at the base of the vertebrate counterparts, suggesting that it represents the archetype of vertebrate promethins. Both Northern blotting and in situ hybridization histochemistry revealed a tissue-specific expression pattern of promethin-like gene, like that of mammalian promethins. This is the first report on invertebrate promethin-like homolog, paving the way for further insights into the evolution and function of promethins.
authors.affiliation: Department of Marine Biology, Ocean University of China, 266003, Qingdao, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: S C
authors.initials: SC
authors.lastname: Zhang
authors.forename: Y J
authors.initials: YJ
authors.lastname: Liang
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D043344:Chordata / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics*; D010802:Phylogeny; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D011506:Proteins; D012333:RNA, Messenger
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