Endogenous lectins from cultured cells. Isolation and characterization of carbohydrate-binding proteins from 3T3 fibroblasts.
Extracts of cultured 3T3 fibroblasts, obtained by homogenization and Triton X-100 solubilization, were fractionated on Sepharose columns covalently derivatized with asialofetuin. Three distinct carbohydrate-binding proteins (CBPs) were purified from the material bound to the affinity column: CBP35 (Mr = 35,000), CBP16 (Mr = 16,000), and CBP13.5 (Mr = 13,500). These CBPs were similar in several key properties. (a) They showed agglutination activity when assayed with rabbit erythrocytes; (b) they all appear to specifically recognize galactose-containing glycoconjugates; (c) they have low isoelectric points, pI 4.5-4.7; (d) their binding activities are rapidly lost in the absence of beta-mercaptoethanol; (e) the CBPs do not interact with each other, and the fractionated proteins can bind to asialofetuin independent of associated polypeptides; and (f) none of the proteins tend to self-associate to form oligomers of identical subunits. Comparisons of these and other properties of the CBPs suggest that CBP16 and CBP13.5 may be the murine counterparts of lactose-specific lectins previously identified in electric eel and in several bovine and avian tissues. In contrast, it appears that CBP35 represents a newly identified protein capable of binding to galactose-containing carbohydrates.
D000818:Animals; D001212:Asialoglycoproteins; D002352:Carrier Proteins / Q000302:isolation & purification*; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D000070821:Discoidins; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D060748:Fetuins; D005347:Fibroblasts / Q000032:analysis; D007526:Isoelectric Point; D037102:Lectins / Q000302:isolation & purification*; D051379:Mice; D008970:Molecular Weight; D015800:Protozoan Proteins; D000509:alpha-Fetoproteins / Q000378:metabolism
D001212:Asialoglycoproteins; D002352:Carrier Proteins; D000070821:Discoidins; D060748:Fetuins; D037102:Lectins; D015800:Protozoan Proteins; D000509:alpha-Fetoproteins; C017029:asialofetuin; D004492:Edetic Acid