title: Ia antigen turnover. II. The kinetics of biosynthesis and release of Ia alpha- and beta-chains by murine spleen cells in culture.
abstract: The kinetics of biosynthesis, release, and turnover of Ia antigens were determined by 3H-leucine labeling, immunoprecipitation and SDS-PAGE analysis. Continuous incorporation and pulse-chase experiments demonstrated that the half-life of the total cell Ia pool was 8 hr, with radiolabeled Ia antigens released from the cell within 4 hr of culture initiation. Both Ia alpha- and beta-chains were released by the cells. I-A antigen turnover was more rapid than I-E antigen turnover. However, detailed comparison of I-A and I-E alpha- and beta-chain biosynthesis demonstrated that the E beta (Ae) chains were synthesized more rapidly than E alpha chains, at rates similar to A alpha- and A beta-chains. Once assembled, however, E alpha- and E beta (Ae)- chains were turned over at the same rate. This kinetic anomaly may reflect post-translational association of polypeptides coded by separate genes into complete I-E antigens.
mesh_terms: D000818:Animals; D000954:Antigens, Surface; D004591:Electrophoresis, Polyacrylamide Gel; D005815:Genetic Code; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology*; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D051379:Mice; D008808:Mice, Inbred CBA; D010452:Peptide Biosynthesis; D011110:Polymorphism, Genetic; D013154:Spleen / Q000276:immunology*; D013997:Time Factors
chemical_list: D000954:Antigens, Surface; D006183:H-2 Antigens; D007930:Leucine