Human Ia alpha- and beta-chains are sulfated.
The human Ia antigens (DR, DQ, and DP), determined by genes with the HLA complex, are heterodimers consisting of a 34,000-Da alpha-chain glycoprotein and a 29,000-Da beta-chain glycoprotein. During the course of studies characterizing a recently described sulfated proteoglycan that is specifically associated with Ia, we discovered that there were also nonproteoglycan sulfated components present in the Ia immunoprecipitates. One-dimensional sodium dodecyl sulfate-gel analysis of these latter sulfated components derived from both DR and DQ immunoprecipitates indicated that these components have mobilities indistinguishable from conventional Ia alpha and beta glycoproteins. Two-dimensional gel analysis confirmed these findings and revealed that Ia-associated invariant proteins are sulfated as well. The sulfate moiety was not removed by endoglycosidase F treatment, suggesting that the protein portion of the molecule was sulfated. These results indicate that Ia alpha-, beta-, and invariant chains can be sulfated and raise the possibility that sulfation may play a role in the physiology of Ia molecules.
D002460:Cell Line; D006026:Glycoside Hydrolases; D006681:HLA-D Antigens / Q000378:metabolism*; D006801:Humans; D007526:Isoelectric Point; D046911:Macromolecular Substances; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008970:Molecular Weight; D013431:Sulfates / Q000378:metabolism*
D006681:HLA-D Antigens; D046911:Macromolecular Substances; D013431:Sulfates; D006026:Glycoside Hydrolases; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase