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Cloning, sequence analysis and expression of a cDNA encoding a novel insulin‐like growth factor binding protein (IGFBP‐2).
Author(s) -
Binkert C.,
Landwehr J.,
Mary J.L.,
Schwander J.,
Heinrich G.
Publication year - 1989
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1989.tb08386.x
Subject(s) - biology , complementary dna , cloning (programming) , sequence (biology) , insulin like growth factor binding protein , genetics , peptide sequence , sequence analysis , computational biology , microbiology and biotechnology , insulin like growth factor , growth factor , gene , computer science , programming language , receptor
Insulin‐like growth factors bind with high affinity to specific binding proteins in extracellular fluids. To identify structural characteristics of IGF‐binding proteins that might define their physiological roles, we determined the complete primary structure of a novel human IGF‐binding protein (IGFBP‐2) from a cloned cDNA. The cDNA encodes a 328 amino acid IGF‐binding protein precursor which contains a 39‐residue signal peptide. The mature 289 amino acid IGFBP‐2 has a predicted Mr of 31,325. Chinese hamster ovary (CHO) cells stably transformed with the IGFBP‐2 cDNA secreted a 36 kd protein which bound, with different affinities, IGFII and IGFI, but did not bind insulin. The predicted protein sequence of this IGF‐binding protein shares extensive amino acid homology (greater than 85%) with the IGF‐binding protein secreted by rat BRL‐3A cells, but less than 40% homology with human IGFBP‐1. Therefore IGFBP‐2, and not IGFBP‐1 as previously suggested, represents the human homologue of the rat BRL‐BP (alpha IGFBP‐2). Moreover, from alignment of the predicted protein sequences of IGFBP‐1 and IGFBP‐2, extensive conservation of the distribution of cysteine residues is observed. Although the overall amino acid homology shared by these proteins is not high, we suggest that they represent a family of structurally related human IGFBPs. Southern blot analysis of human DNA demonstrates that IGFBP‐2 is encoded by a single‐copy gene, different from that of IGFBP‐1.