ALPHA-2-MACROGLOBULIN AND THE QUESTION OF A PROTEIN CARRIER FOR INSULIN IN HUMAN SERUM

Publisher Website
Google Scholar
Abstract
Blood serum from presumably normal individuals was investigated for its insulin-I131 binding capacity by Immunoelectrophoresis and subsequent radioautography, by immunoprecipitation in the test tube, and by preparative ultracentrifugation.Binding of radioactive insulin to alpha-2-macrogiobulin was demonstrated by immunoelectrophoresis, but the fact that radioactivity was present also in a number of other protein precipitates weakened the argument for a specific insulin carrier in blood. Nonspecific trapping of radioactive material may have occurred in the course of formation of protein precipitates in agar gel because immunoprecipitates produced in the test tube with the same polyvalent antiserum did not contain appreciable amounts of radioactivity.Results of experiments in the preparative ultracentrifuge indicated that neither multiple dilutions nor addition of pure human alpha-2-macroglobulin to serum produced measurable differences in the distribution of radioactivity following incubation and spinning with a constant amount of insulin-I131.The results of these studies do not lend support to the concept of alpha-2-macroglobulin being a specific protein carrier of insulin in blood.

This publication has 4 references indexed in Scilit: