ISSN:
1365-2958
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
Dictyostelium dfscoideum synthesizes a 23000 Mr protein, p23dd-ras, closely related to the mammalian oncogene-encoded protein p21ras. To investigate the subcellular localization of P23dd-ras, conditions were optimized to reduce protein degradation following cell breakage. Subcellular fractionation of D. discoideum showed that p23dd-ras was associated predominantly with the membrane fraction during both vegetative growth and differentiation, in the absence of suitable protease inhibitors considerable amounts of a truncated form of p23dd-ras were recovered in the cytosol fraction, suggesting that intact p23dd-ras is attached to the membrane by a short terminal peptide sequence. Radio-isotope labelilng of D. discoideum with myristic acid or palmitic acid in the presence of excess un-labelled acetate resulted in radio-isotope incorporation into a select group of proteins including p23dd-ras. No acyl label appeared in the truncated cytoplasmic form of p23dd-ras when ceil breakage was performed In the absence of suitable protease inhibitors, indicating that the acyl group is associated with the short terminal peptide that is cleaved. These data suggest that p23dd-ras like its mammailan counterpart, is acylated and associated with the plasma membrane. There was no evidence during a 30-minute pulse of methionine for a cytoplasmic precursor to the membrane-bound p23dd-ras suggesting that the turnover of the presumptive precursor must be much more rapid in D. discoideum than for pro-p21ras in mammalian cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2958.1987.tb01941.x
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