title: Chicken and Xenopus mannose 6-phosphate receptors fail to bind insulin-like growth factor II.
abstract: The recent demonstration that a single mammalian receptor protein binds both mannose 6-phosphate (Man-6-P) and insulin-like growth factor II (IGF-II) with high affinity has suggested a multifunctional physiological role for this receptor, possibly including signal transduction. In order to better understand the functions of this receptor, we have investigated the properties of Man-6-P receptors from non-mammalian species. Receptors were affinity-purified from Triton X-100 extracts of total membranes from Xenopus and chicken liver as well as rat placenta using pentamannosyl 6-phosphate-Sepharose. The Man-6-P receptor was adsorbed to the pentamannosyl 6-phosphate-Sepharose and specifically eluted by Man-6-P in all three species, as evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining. When the purified receptors from these three species were cross-linked to 125I-IGF-II with disuccinimidyl suberate, only receptors isolated from rat membranes were affinity-labeled. To further evaluate the properties of these Man-6-P receptors, binding of 125I-rat-IGF-II and 125I-chicken Tyr-Gly-Thr-Ala-IGF-II to purified receptors from Xenopus, chicken, and rat was evaluated by polyethylene glycol precipitation. Only the rat Man-6-P receptor exhibited detectable binding of 125I-IGF-II. These data suggest that the emergence of a high affinity IGF-II binding site on the Man-6-P receptor occurred in evolution after the divergence of mammals from other vertebrates. Thus, the biological actions of IGF-II in chickens and frogs appear to be initiated by the type I IGF receptor.
authors.affiliation: Department of Biochemistry, University of Massachusetts Medical Center, Worcester 01655.
authors.forename: K B
authors.initials: KB
authors.lastname: Clairmont
authors.forename: M P
authors.initials: MP
authors.lastname: Czech
mesh_terms: D000818:Animals; D002645:Chickens; D002846:Chromatography, Affinity; D005260:Female; D006600:Hexosephosphates / Q000378:metabolism*; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D007700:Kinetics; D008360:Mannosephosphates / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D008970:Molecular Weight; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011485:Protein Binding; D051381:Rats; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*; D013002:Somatomedins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D006600:Hexosephosphates; D008360:Mannosephosphates; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface; D013002:Somatomedins; D007335:Insulin-Like Growth Factor II