PLANT PHYSIOLOGY , Vol 111, Issue 2 559-568, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Association of Plant p40 Protein with Ribosomes Is Enhanced When Polyribosomes Form during Periods of Active Tissue Growth
M. Garcia-Hernandez, E. Davies, T. I. Baskin and P. E. Staswick
Department of Agronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0915 (M.G.-H., P.E.S.)
p40s are acidic proteins of eukaryotic cells occurring either free in the
cytoplasm or in association with ribosomes, the latter occurring in both
monosomes and polysomes. p40s may play a role in the regulation of protein
synthesis, although the exact mechanism is not known. Leaves of all 10
plant species examined here, including both monocots and dicots, contained
proteins detected on immunoblots with Arabidopsis thaliana p40 antiserum.
The number and apparent size of the protein bands were variable even among
closely related species. Abundance of p40 relative to ribosomal content
during soybean (Glycine max L.) seed germination and during seed and leaf
development was examined. p40 abundance correlated with periods of active
tissue growth and high polysome content. The plant growth regulator indole
acetic acid caused an increase in polysome formation in etiolated pea
(Pisum sativum L.) plants and a concomitant recruitment of p40 into
polysomes. Subcellular localization at the microscopy level indicated that
the pattern of p40 staining is very similar to that for RNA, except that
p40 is excluded from the nucleus. These data suggest that p40 is an
accessory protein of the ribosome that might play a role in plant growth
and development.
