Document Detail

The first complete cDNA sequence of the hemocyanin from a bivalve, the protobranch Nucula nucleus.
MedLine Citation:
PMID:  17476452     Owner:  NLM     Status:  MEDLINE    
By cDNA sequencing we have achieved the first, and complete, hemocyanin sequence of a bivalve (Nucula nucleus). This extracellular oxygen-binding protein consists of two immunologically distinguishable isoforms, here termed NnH1 and NnH2. They share a mean sequence identity of 61%, both contain a linear arrangement of eight paralogous, ca.50-kDa functional units (FUs a-h), and in both isoforms the C-terminal FU-h possesses an extension of ca. 100 amino acids. The cDNA of NnH1 comprises 11,090 bp, subdivided into a 5'utr of 75 bp, a 3'utr of 791 bp, and an open reading frame for a signal peptide of 19 amino acids plus a polypeptide of 3389 amino acids (Mr = 385 kDa). The cDNA of NnH2 comprises 10,849 bp, subdivided into a 5'utr of 47 bp, a 3'utr of 647 bp, and an open reading frame for a signal peptide of 16 amino acids plus a polypeptide of 3369 amino acids (Mr = 387 kDa). In contrast to other molluscan hemocyanins, which are highly glycosylated, the bivalve hemocyanin sequence exhibits only four potential N-glycosylation sites, and within both isoforms a peculiar indel is present, surrounding the highly conserved copper-binding site CuA. Phylogenetic analyses of NnH1 and NnH2, compared to the known hemocyanin sequences of gastropods and cephalopods, reveal a statistically sound closer relationship between gastropod and protobranch hemocyanin than to cephalopod hemocyanin. Assuming a molecular clock, the last common ancestor of protobranch and gastropods lived 494 million +/- 50 million years ago, in conformity with fossil records from the late Cambrian.
Sandra Bergmann; Jürgen Markl; Bernhard Lieb
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-05-02
Journal Detail:
Title:  Journal of molecular evolution     Volume:  64     ISSN:  0022-2844     ISO Abbreviation:  J. Mol. Evol.     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-05-07     Completed Date:  2007-08-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0360051     Medline TA:  J Mol Evol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  500-10     Citation Subset:  IM    
Institute of Zoology, Johannes Gutenberg University, 55099 Mainz, Germany.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/AJ786639;  AJ786640
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MeSH Terms
Amino Acid Sequence
Base Sequence
Bivalvia / genetics*
DNA, Complementary / genetics*
Gene Expression Regulation
Hemocyanin / chemistry,  genetics*,  metabolism
Models, Molecular
Molecular Sequence Data
Protein Conformation
Reg. No./Substance:
0/DNA, Complementary; 9013-72-3/Hemocyanin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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