Novel isoprenylated proteins identified by an expression library screen.
Isoprenylated proteins are involved in eukaryotic cell growth and signal transduction. The protein determinant for prenylation is a short carboxyl-terminal motif containing a cysteine, to which the isoprenoid is covalently attached via thioether linkage. To date, isoprenylated proteins have almost all been identified by demonstrating the attachment of an isoprenoid to previously known proteins. Thus, many isoprenylated proteins probably remain undiscovered. To identify novel isoprenylated proteins for subsequent biochemical study, colony blots of a Glycine max cDNA expression library were [3H]farnesyl-labeled in vitro. Proteins identified by this screen contained several different carboxyl termini that conform to consensus farnesylation motifs. These proteins included known farnesylated proteins (DnaJ homologs) and several novel proteins, two of which contained six or more tandem repeats of a hexapeptide having the consensus sequence (E/G)(G/P)EK(P/K)K. Thus, plants contain a diverse array of genes encoding farnesylated proteins, and our results indicate that fundamental differences in the identities of farnesylated proteins may exist between plants and other eukaryotes. Expression library screening by direct labeling can be adapted to identify isoprenylated proteins from other organisms, as well as proteins with other post-translational modifications.
Biermann
B J
BJ
Department of Biology, Indiana University-Purdue University, Indianapolis 46202-5132.
Morehead
T A
TA
Tate
S E
SE
Price
J R
JR
Randall
S K
SK
Crowell
D N
DN
D019883:Alkyl and Aryl Transferases; D000595:Amino Acid Sequence; D016384:Consensus Sequence; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005204:Farnesol / Q000378:metabolism*; D015723:Gene Library; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000302:isolation & purification; D017368:Protein Prenylation; D012641:Selection, Genetic; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000737:chemistry / Q000235:genetics*; D014166:Transferases / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics
C083280:ANJ1 protein, Atriplex nummularia; D018076:DNA, Complementary; D010940:Plant Proteins; D005204:Farnesol; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C064911:p21(ras) farnesyl-protein transferase; D018631:ras Proteins