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Abstract
A Stimulatior Protein of Rubber Biosynthesis from Hevea
Brasiliensis Latex
A rubber biosynthesis stimulatior protein (RBSP)
from the C-serum of Hevea brasiliensis latex was purified and characterised.
This proteinaceous factor stimulates the incorporation of isopentenyl diphosphate
into rubber and thereby enhances the rate of rubber biosynthesis. The heat
stable RBSP is shown to have a molecular weight of 13 068 Da by mass spectroscopy.
Amino acid sequence of peptide fragments obtained from trypsin digestion
revealed regions of sequence similar to eukaryotic Initiation Factor 5A
(eIF-5A), present in alfalfa (Medicago sativa), tobacco (Nicotiana tabacum
and Nicotiana plumbaginifolia), Arabidopsis thaliana and potato (Solanum
tuberosum). Three Hevea eIF-5A clones were obtained from screening a latex
cDNA library with a partial eIF-5A cDNA from tobacco. Small variations in
their DNA sequences indicated that they represented three different isoforms.

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