PLANT PHYSIOLOGY , Vol 106, Issue 3 1157-1162, Copyright © 1994 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
Arabidopsis thaliana Expresses Three Divergent Srp54 Genes
B. Chu, J. T. Lindstrom and F. C. Belanger
Plant Science Department, Rutgers University, New Brunswick, New Jersey 08903-0231
The Arabidopsis thaliana Srp54 gene family was determined to consist of
three genes, all of which were cloned and sequenced. In addition, cDNAs
corresponding to two of the genes were obtained. To our knowledge this is
the first description of multiple Srp54 genes within an organism. In
contrast to the situation in mammals, where there are only three amino acid
differences between the mouse and canine sequences, there was significant
amino acid sequence diversity among the genes, particularly in the
methionine-rich region of the protein, which is the region responsible for
binding to the 7S RNA of the signal recognition particle and to the signal
sequence of newly synthesized proteins. The amino acid sequences of the
GTP-binding domains of the three clones were 86% identical, whereas the
methionine-rich domains were only 65% identical. RNA gel blots of various
tissues and developmental stages hybridized with gene-specific probes
revealed that all three genes were expressed in all the tissues
investigated. There were, however, quantitative differences in expression
levels.
