Nucleotide sequences at the 5'termini of rabbit alpha and beta globin mRNA.

The nucleotide sequences at the 5' termini of rabbit alpha and beta globin mRNAs have been determined. Periodate oxidation of globin mRNA followed by reduction with 3H-sodium borohydride and subsequent analysis of the 3H-labeled mRNA reveals the presence of the "cap" structure m7G5'ppp- blocking the 5' terminus. After periodate oxidation, beta elimination, and phosphomonoesterase treatment to remove the m7G5'ppp- "cap," the 5' end of globin mRNA was labeled with 32P using gamma-32P-ATP and T4 polynucleotide kinase. The 5'-32P-labeled alpha and beta globin mRNAs were then resolved from each other by polyacrylamide gel electrophoresis under denaturing conditions and sequenced separately. The 5' terminal nucleotide sequences determined are: alpha--m7G5'ppp5m6AmC(m)ACUUCUGG- BETA--M7G5'ppp5m6AmC(m) ACUUGCUUUUGACACAA Besides the m7G "cap" structure, the two sequences are identical for the first six nucleotides and then diverge. No initiator codon is present within the first ten nucleotides from the 5' end of the alpha globin mRNA, and the first nineteen nucleotides from the 5' end of beta globin mRNA.