We show that the absence of a Watson-Crick base pair at the end of the amino acid acceptor stem, which is a hallmark of all prokaryotic initiator tRNAs, is one of the key features that prevents them from acting as an elongator in protein synthesis. We generated mutants of Escherichia coli formylmethionine tRNA that have a base pair at the end of the acceptor stem. The mutants generated were C1-...

Initiator tRNAs are used exclusively for initiation of protein synthesis and not for elongation. We show that both Escherichia coli and eukaryotic initiator tRNAs have negative determinants, at the same positions, that block their activity in elongation. The primary negative determinant in E. coli initiator tRNA is the C1xA72 mismatch at the end of the acceptor stem. The primary negative determ...

Asymmetric stem cell division is often accompanied by stereotypical inheritance of the mother and daughter centrosomes. However, it remains unknown whether and how stem cell centrosomes are uniquely regulated and how this regulation may contribute to stem cell fate. Here we identify Klp10A, a microtubule-depolymerizing kinesin of the kinesin-13 family, as the first protein enriched in the stem ...

A bioassay employing green or etiolated cuttings of Phaseolus aureus Roxb. was developed for determining malformin-induced growth stimulation in light. Growth enhancement of green cuttings was more rapid and relatively greater than that of etiolated cuttings. Cuttings from green seedlings responded less as seedlings aged; those from etiolated seedlings responded more. Malformin also stimulated ...