title: A crayfish insulin-like-binding protein: another piece in the androgenic gland insulin-like hormone puzzle is revealed.
abstract: Across the animal kingdom, the involvement of insulin-like peptide (ILP) signaling in sex-related differentiation processes is attracting increasing attention. Recently, a gender-specific ILP was identified as the androgenic sex hormone in Crustacea. However, moieties modulating the actions of this androgenic insulin-like growth factor were yet to be revealed. Through molecular screening of an androgenic gland (AG) cDNA library prepared from the crayfish Cherax quadricarinatus, we have identified a novel insulin-like growth factor-binding protein (IGFBP) termed Cq-IGFBP. Based on bioinformatics analyses, the deduced Cq-IGFBP was shown to share high sequence homology with IGFBP family members from both invertebrates and vertebrates. The protein also includes a sequence determinant proven crucial for ligand binding, which according to three-dimensional modeling is assigned to the exposed outer surface of the protein. Recombinant Cq-IGFBP (rCq-IGFBP) protein was produced and, using a "pulldown" methodology, was shown to specifically interact with the insulin-like AG hormone of the crayfish (Cq-IAG). Particularly, using both mass spectral analysis and an immunological tool, rCq-IGFBP was shown to bind the Cq-IAG prohormone. Furthermore, a peptide corresponding to residues 23-38 of the Cq-IAG A-chain was found sufficient for in vitro recognition by rCq-IGFBP. Cq-IGFBP is the first IGFBP family member shown to specifically interact with a gender-specific ILP. Unlike their ILP ligands, IGFBPs are highly conserved across evolution, from ancient arthropods, like crustaceans, to humans. Such conservation places ILP signaling at the center of sex-related phenomena in early animal development.
authors.affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
authors.forename: Ohad
authors.initials: O
authors.lastname: Rosen
authors.forename: Simy
authors.initials: S
authors.lastname: Weil
authors.forename: Rivka
authors.initials: R
authors.lastname: Manor
authors.forename: Ziv
authors.initials: Z
authors.lastname: Roth
authors.forename: Isam
authors.initials: I
authors.lastname: Khalaila
authors.forename: Amir
authors.initials: A
authors.lastname: Sagi
mesh_terms: D000595:Amino Acid Sequence; D000728:Androgens / Q000502:physiology*; D000818:Animals; D003400:Astacoidea; D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D005260:Female; D007328:Insulin / Q000502:physiology*; D018969:Insulin-Like Growth Factor Binding Proteins / Q000502:physiology*; D008297:Male; D016133:Polymerase Chain Reaction
chemical_list: D000728:Androgens; D017931:DNA Primers; D018076:DNA, Complementary; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins
keywords: Insulin-like Growth Factor (IGF); Ligand-binding Protein; Physiology; Recombinant Protein Expression; Reproduction