The selection of the first AUG as the initiator of eucaryotic mRNAs translation is favored by a 5′-terminal cap group and a purine in the -3′ position

We have constructed a series of plasmids containing variations in the DNA that codes for the translation initiation region of preproparathyroid hormone. Gel electrophoretic analyses of the character and extent of synthesis of various modified preproparathyroid hormone like proteins derived from the mRNAs transcribed from these plasmids reveal that the presence of a 5′-terminal cap group on mRNA's facilitates recognition of the most 5′-terminal AUG sequence on a mRNA and that AUG sequences within the consensus sequence PuXXAUGPu are favored sites for the initiation of mRNA translation.