DEVELOPMENTAL BIOLOGY 64, 265-272 (1978) Developmentally Regulated Lectins from Chick Muscle, Brain, and Liver Have Similar Chemical and Immunological Properties’ DAVID KOBILER,~ ERIC C. BEYER,~ AND SAMUEL H. BARONDES Department of Psychiatry, University of California at San Diego, La Jolla, California 92093 Received December 19, 1977; accepted January 19, 1978 Developmentally regulated lectins in extracts from brain, liver and muscle of 16-day-old chick embryos and liver of 7-day-old chicks have been purified by affinity chromatography. The purified preparations from the different tissues were indistinguishable in molecular weight and isoelectric point. The lectins could also not be distinguished when tested as antigens with antiserum raised against highly purified muscle lectin. This apparent identity was indicated both in double gel diffusion tests and by determination of the antibody-mediated inhibition of hemagglutination activity of the various lectins. Thiodigalactoside and lactose were potent inhibitors of the lectins from all sources. Galactose was a less potent inhibitor, especially with preparations from embryonic liver. After isoelectric focusing of these purified preparations, they all showed reduced and equivalent galactose sensitivity. Since the lectins from the different tissues appear identical, there is presently no basis to infer that they impart qualitative uniqueness to these tissues during differentiation. INTRODUCTION Embryonic chick muscle (Nowak et aZ., 1976; Den et al., 1976), heart, liver, and brain (Kobiler and Barondes, 1977) contain carbohydrate-binding proteins called lec- tins, which can be assayed as hemaggluti- nins. The specific activities of the lectins change markedly with differentiation of these tissues (Nowak et al., 1976; Den et al., 1976; Kobiler and Barondes, 1977). The lectin from embryonic chick muscle has been purified by affinity chromatography (Nowak et al., 1977). An antibody raised to this pure protein binds to the surface of differentiating muscle cells (Nowak et al., 1977). This and other evidence (Gartner and Podleski, 1975) suggest that the lectin may play a role in cellular interactions in muscle, perhaps by interacting with specific polysaccharide receptors on cells with which it comes in contact. A role for devel- ’ Supported by USPHS Grant MH 18282 and a grant from the McKnight Foundation. * A Chaim Weizmann Fellow. “A Medical Scientist Training Program trainee supported by USPHS Training Grant GM07198 opmentally regulated endogenous cell sur- face lectins in cellular interactions is sug- gested from extensive work with cellular slime molds (Barondes and Rosen, 1976). Developmentally regulated lectins have been purified and characterized from four species of these simple eukaryotes (Simp- son et al., 1974, 1975; Frazier et al., 1976; Barondes and Haywood, 1978). Lectins from each species have been shown to be closely related but clearly distinct proteins by physicochemical and immunological cri- teria (Barondes and Haywood, 1978), as well as by the relative potency of specific saccharides to inhibit their activity as he- magglutinins (Rosen et al., 1975; Barondes and Haywood, 1978). Since the lectins are found on the surface of cohesive slime mold cells, their unique characteristics might contribute to the species-specific properties of these cell surfaces. Given these findings with slime molds, we sought to determine the relationship of the developmentally regulated lectins from three embryonic chick tissues, skeletal muscle, liver, and brain. Might they impart 265 0012-1606/78/0642-0265$02.00/O Copyright 0 1978 by Academic Press, Inc. All rights of reproduction in any form reserved.