Uttam L. RajBhandary studied how RNA structure determines recognition by proteins, particularly the different jobs of transfer RNA during biological translation. MIT's named profile connects Uttam RajBhandary with publications credited to RajBhandary, UL, including work on initiator transfer RNA.[ref]
Uttam RajBhandary faculty profile at MIT. Research Summary and Key Publications, especially Initiator transfer RNAs
With B. L. Seong, he tested whether conserved base pairs in the anticodon stem help distinguish an initiator transfer RNA from an elongator transfer RNA. The 1987 study replaced one, two or three G–C pairs with the corresponding elongator pattern and examined purified transfer RNA variants. Their initiation activity decreased even though they could still bind bacterial initiation factor IF2; AUG-dependent binding at the ribosomal P site was impaired.[ref]
Escherichia coli formylmethionine tRNA: mutations in GGGCCC sequence conserved in anticodon stem of initiator tRNAs affect initiation of protein synthesis and conformation of anticodon loop by B. L. Seong and U. L. RajBhandary. Abstract, stem substitutions and comparison of initiation-factor and P-site binding
The experiment separates carrying the right amino acid from being recognized at the right step. For an original counting example, suppose 100 charged carriers are presented to a simplified initiation assay, 80 reach a tested binding state, and 20 of those proceed to productive initiation. The productive fraction is . Equal charging or equal binding at an earlier state would not establish equal productive output. These stipulated counts illustrate sequential selection; they are not measured values from the paper.
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