Identification and isolation of protamine messenger ribonucleoprotein particles from rainbow trout testis

Treatment of rainbow trout testis polyribosomes with ethylenediaminetetraacetic acid released polyadenylated protamine messenger RNA in the form of a ribonucleoprotein (mRNP) particle. This mRNP particle which sedimented at 12-14 S could be identified by hybridization to [3H]poly(U) and was partially purified by two successive sucrose gradient sedimentations. When RNA was extracted from the mRNP particle and used as a template in the wheat germ cell-free protein synthesizing system the sole product of translation was protamine. Of this RNA, 30% contained poly(A) sequences and was shown to comigrate with polyadenylated protamine messenger RNA during polyacrylamide gel electrophoresis. When the proteins of the mRNP particle were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the two prominent polypeptides with apparent molecular weights of 73 000 and 29 000 appeared reproducibly. Treatment of trout testis polyribosomes with puromycin in the presence of 0.5 M KCl released a smaller (8-10S) mRNP particle which was similarly shown to contain protamine messenger RNA. Trout testis postribosomal supernatant fraction possessed 16-18S mRNP particles containing polyadenylated RNA which cosedimented with protamine messenger RNA when the particles were dissociated with sodium dodecyl sulfate.