Biochemical characterization of a family of proteins that stabilizes a plant Ran protein in its GTP-bound conformation.
Ran-binding proteins (RanBP) are a group of proteins that bind to Ran (Ras-related nuclear small G-protein) and thus control the GTP/GDP-bound states of the Ran and couple the Ran GTPase cycle to cellular processes. In an effort to identify potential downstream effectors for PsRan1-dependent cellular processes, we detected a group of pea Ran (PsRan1)-binding proteins and characterized their biochemical activities. A Ran overlay assay using [(32)P-GTP]-labeled PsRan1 revealed three PsRan1-binding proteins (33, 45, and 85kDa in size) from total protein extracts of dark-grown pea plumules. These proteins bound preferentially to the Ran-GTP over Ran-GDP conformation and subsequently stabilized its GTP-bound status. We propose that they are a family of proteins that maintain the Ran protein in the active conformation and are potential downstream mediators for PsRan1-dependent cellular processes. Our report provides the basis for characterizing and dissecting Ran downstream targets and Ran-mediated events, and it thus facilitates our understanding about the roles played by Ran/RanBP signaling pathways during plant growth and development.
Lee
Y
Y
Department of Biological Sciences, Yonsei University, 234 Heungup-Myun, 220710 Wonju-Si, Korea.
Roux
S J
SJ
Kim
S-H
SH
D004492:Edetic Acid / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism*; D007700:Kinetics; D018532:Pisum sativum / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011487:Protein Conformation; D020931:ran GTP-Binding Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D010940:Plant Proteins; D006160:Guanosine Triphosphate; D004492:Edetic Acid; D020931:ran GTP-Binding Protein