Author
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Li, Ming |
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Ford, Johny |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 5/9/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Several investigators proposed that both the alpha and beta subunits of all pituitary, glycoprotein hormones evolved from a common ancestral gene. However, such a proposal has never been examined extensively using available nucleotide and product amino acid sequence information from different species. Recently, Wako and Ishii (1995) conducted a phylogenetic analysis of this family, but only a small number of amino aci sequences for the beta subunit with limited residues was analyzed, and the statistical accuracy of the phylogenetic tree was unclear. In the present study, 57 nucleotide sequences of the coding region of this hormone family representing a broad spectrum of species from fish, amphibians, birds, to mammals, were compared. An essentially identical tree was produced by both the nucleotide and amino acid sequences which yielded four major groups (Alpha, TSH beta, FSH beta/related, LH beta/related). Some of these groups scan further be divided into 2 or 3 subgroups. The reliability of the phylogenetic tree was tested by a bootstrap technique with 1,000 replicates. Our results support the proposal that all subunits of this hormone family evolved from a common ancestor by gene duplications. Furthermore, we found that: 1) FSH beta is more related to TSH beta rather than to LH beta; 2) most fish gonadotropin type Is are highly related to mammalian FSH beta while fish type II relates to mammalian LH beta/CG beta; and 3) the alpha-subunit for species with chorionic gonadotropin (CG; i.e., human and horse) formed a subgroup distinct from other mammals without a CG gene. |
