Novel intermediates in the synthesis of maltose-binding protein in Escherichia coli.

Nascent intermediates in the synthesis of maltose-binding protein, a periplasmic protein in Escherichia coli, were demonstrated both in vivo and in vitro. They are likely to result from a drastic reduction in the rate of elongation at specific sites on the mRNA leading to detectable accumulation of distinct species of incomplete polypeptides. In order to reach its final destination in the periplasmic space, maltose-binding protein is transferred across the cytoplasmic membrane as it is elongated. It is possible that variations in the rate of elongation are involved in this export process.