Reference "Barley alpha-amylase genes. Quantitative comparison of steady-state mRNA levels from individual members of the two different families expressed in aleurone cells"

Reference ID

8797

Title

Barley alpha-amylase genes. Quantitative comparison of steady-state mRNA levels from individual members of the two different families expressed in aleurone cells

Source

The Journal of biological chemistry, 1988, vol. 263, pp. 18953-18960

Authors (2)

Khursheed-B

Rogers-J-C

Abstract

We have cloned and sequenced two barley alpha-amylase genes belonging to the
high pI isozyme family, one of which, Amy6-4, corresponds to a cDNA previously
characterized by our laboratory. A 750-base pair probe from Amy6-4, representing
primarily the promoter/upstream sequences cross-hybridizes on genomic Southern
blots under stringent conditions to five other genes or pseudogenes; this
demonstrates that the promoter/upstream region in these different members of the
gene family is highly conserved. In contrast, this probe hybridizes very poorly
to the genomic fragment containing the other cloned high pI gene, Amy46, a
finding consistent with substantial divergence of sequence about 200 base pairs
upstream from the TATA box of each. We compared steady-state mRNA levels from
these individual genes to levels for mRNAs from two low pI alpha-amylase genes
and from the single copy gene for aleurain, a thiol protease, using quantitative
S1 nuclease protection assays. We found, in RNA from aleurone cells treated with
gibberellic acid for 19-24 h, that the two low pI alpha-amylase mRNAs are each
about five times more abundant than Amy6-4 or aleurain, which are, in turn,
about 10 times more abundant than Amy46. These results indicate that as many as
seven closely related high pI genes are needed to provide mRNA levels
approaching those from the two low pI genes. We speculate that the substantially
lower level of expression of Amy46 may be related to its divergent sequence
upstream from the promoter.