Protamine messenger RNA: partial purification and characterization of a heterogeneous family of polyadenylated messenger components

Poly(A)+ protamine mRNA (pmRNA) components were isolated after separation on denaturing preparative polyacrylamide gels. The four size classes of protamine mRNA described previously were found to contain poly(A) tracts of different lengths. The pmRNA1 was found to be associated with (A)110, pmRNA2 with (A)90, pmRNA3 with (A)85, and pmRNA4 with (A)69. Following deadenylation with RNase H after duplex formation with oligo-dT, the isolated mRNAs were found to be still heterogeneous, although highly enriched in certain of the deadenylated components. DNA complementary to the isolated mRNAs (cDNA) was synthesized in vitro. Following depurination, the oligopyrimidine maps indicated that C7T4, corresponding to an Arg-Arg-Gly-Gly sequence in protamine and originally thought to be characteristic of all mRNA components, is present in only one or possibly two of the components. Cross-hybridizations between the cDNAs and the four poly(A)+ pmRNAs indicated that a basic polynucleotide unit of substantial length is common to all four mRNAs and that the existing nucleotide sequence variations probably originate from one or both of the non-coding portions of the mRNA molecules.