Partial purification, characterization and cell-free translation of mRNAs coding for H-2d antigens

Microsomal RNA from SL2 cells was fractionated on oligo(dT)cellulose into three fractions: I was very similar to the non-fractionated RNA, II contained 28S and 18S rRNA, III [poly(A)RNA] of 4 - 50S, constituted 1.0-2.1% of the total RNA pool and was still contaminated with rRNAs. The last fraction was synthesized at the highest rate. Anti-H-2d serum precipitated cell-free translation products of 17S (heavy chain) and 10S (beta 2-microglobulin) mRNA fractions obtained by centrifugation on 10-30% linear sucrose gradient. beta 2-Microglobulin synthesis was 5-fold higher as compared with the heavy chain synthesis. Anti-H-2d serum precipitated translation products with Mr of 47 000-48 000 (H-2Dd and H-2Kd heavy chains) and 12 000 (beta 2-microglobulin). With liver mRNA, the patterns of translation products were identical, but beta 2-microglobulin synthesis was lower by a half than heavy chain synthesis. H-2d heavy chain messenger constituted 0.3-0.4% of the enriched fraction and was purified 15-20--fold.