Positive versus negative signaling of LET-23: regulation through the adaptor protein, SEM-5.
Worby and Margolis highlight advances in our understanding of signaling from growth factor receptors using the worm Caenorhabditis elegans as a model organism. ARK-1, a cytoplasmic tyrosine kinase, appears to be a negative regulator of multiple pathways in C. elegans. The authors discuss several models for how this negative regulation may occur. The adaptor protein (Grb2 in mammals or SEM-5 in C. elegans) may serve as a regulated scaffold for the binding of other signaling proteins that include both positive (Ras) and negative (ACK) regulators. Thus, Grb2 may function in a cellular decision point for transducing the incoming signals.
Worby
C
C
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA. cdworby@umich.edu
Margolis
B
B
D000818:Animals; D017173:Caenorhabditis elegans / Q000737:chemistry / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D066246:ErbB Receptors / Q000502:physiology*; D015801:Helminth Proteins / Q000502:physiology*; D006801:Humans; D015398:Signal Transduction / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; C085751:Sem-5 protein, C elegans; D066246:ErbB Receptors; C085873:let-23 protein, C elegans