Reference "Analysis of sequence microheterogeneity among zein messenger RNAs"

Reference ID

7397

Title

Analysis of sequence microheterogeneity among zein messenger RNAs

Source

The Journal of biological chemistry, 1982, vol. 257, pp. 9976-9983

Authors (2)

Marks-M-D

Larkins-B-A

Abstract

We have synthesized cDNA clones for maize zein proteins using mRNAs purified
from developing endosperm. Analysis of these clones by in vitro translation of
hybrid-selected mRNAs suggested differences in sequence homology among the mRNAs
for the different molecular weight zein polypeptides. These differences were
also apparent in restriction maps of clones corresponding to the Mr = 22,000,
19,000, and 15,000 zeins. Using radioactive cDNA inserts as probes, we measured
the extent of sequence homology among zein clones with a sensitive dot
hybridization procedure. By this analysis, it was possible to distinguish clones
corresponding to the different molecular weight zeins at low (Tm - 49 degrees C)
to moderate (Tm - 35 degrees C) criteria, while under more stringent conditions
(Tm - 20 degrees C), distinctions could be made between zein sequences within a
molecular weight group. This analysis distinguish three different mRNAs for each
of the Mr = 22,000 and Mr = 19,000 zeins, but only one was detected for the Mr =
15,000 zein. Comparison of the nucleotide sequences of clones for the Mr =
22,000 and Mr = 19,000 zeins showed about 60% homology throughout the coding
regions. This analysis also revealed the presence of short repetitive nucleotide
sequences corresponding to tandem repeats of approximately 20 amino acids in
both groups of proteins.