|
|
![]() |
|
|||
| Home Help Feedback Subscriptions Archive Search Table of Contents | |||||
Journal of Cell Science, Vol 107, Issue 1 195-204, Copyright © 1994 by Company of Biologists
JOURNAL ARTICLES |
SM Strittmatter, D Valenzuela and MC Fishman
Developmental Biology Laboratory, Massachusetts General Hospital, Charlestown.
GAP-43 is a neuronal protein that is believed to be important to neuronal growth and nerve terminal plasticity. It is enriched on the inner surface of growth cone membranes, a localization that may depend upon palmitoylation of Cys3 and Cys4. It is a major substrate for protein kinase C, which phosphorylates Ser41. Isolated GAP-43 can bind to actin and to calmodulin, and can activate the heterotrimeric GTP-binding proteins, G(o) and Gi. A peptide consisting of the GAP-43 sequence 39-55 binds calmodulin, and an amino-terminal GAP-43 (1-10) peptide activates G(o), suggesting that these stretches may be functional domains of the intact protein. When expressed in non-neuronal cells, GAP-43 enhances filopodial extension and has effects upon cell spreading. We have examined the effects of various GAP-43 domains upon this assay, by expression of GAP-43, GAP-43 mutant proteins, and GAP-43-CAT fusion proteins in COS-7 cells. We find that the amino terminus (Met-Leu-Cys-Cys-Met-Arg-Arg-Thr-Lys-Gln) is an important contributor to these effects on cell shape. A GAP-43 protein mutant in Cys3 and Cys4 does not bind to the membrane, and is inactive. Mutants in Arg6 or Lys9 also are inactive, although they remain localized to particulate fractions; Arg7 mutants are active. A chimeric gene consisting of GAP-43 (1-10) fused to chloramphenicol acetyl transferase (CAT) also causes cell shape changes. As for GAP-43, the effects of this fusion protein are abolished by mutations of Cys3, Cys4, Arg6 or Lys9, but not by mutation of Arg7. Therefore, the cell surface activity of transfected GAP-43 depends upon its amino terminus, although other domains may regulate it in this regard. Since the amino-terminal domain includes the peptide stretch known to be capable of activating G(o) and Gi, we examined the effect of GAP-43 on a Gi-regulated second messenger system, the inhibition of cAMP production in A431 cells. A431 cells stably transfected with GAP-43 spread less well than do controls. In addition, they evidence decreased levels of forskolin-stimulated cAMP, consistent with chronic stimulation of Gi. Stimulation of adenylate cyclase by isoproterenol reverses the GAP-43-induced changes in cell shape. This suggests that G protein stimulation is involved in GAP-43 effects upon cell shape.
This article has been cited by other articles:
![]() |
C. M. Paden, J. A. Watt, T. H. Selong, C. L. Paterson, and H. J. Cranston The Neuronal Growth-Associated Protein (GAP)-43 Is Expressed by Corticotrophs in the Rat Anterior Pituitary After Adrenalectomy Endocrinology, February 1, 2006; 147(2): 952 - 958. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Kutzleb, G. Sanders, R. Yamamoto, X. Wang, B. Lichte, E. Petrasch-Parwez, and M. W. Kilimann Paralemmin, a Prenyl-Palmitoyl-anchored Phosphoprotein Abundant in Neurons and Implicated in Plasma Membrane Dynamics and Cell Process Formation J. Cell Biol., November 2, 1998; 143(3): 795 - 813. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. H. J. Aarts, L. H. Schrama, W. J. Hage, J. L. Bos, W. H. Gispen, and P. Schotman B-50/GAP-43-induced Formation of Filopodia Depends on Rho-GTPase Mol. Biol. Cell, June 1, 1998; 9(6): 1279 - 1292. [Abstract] [Full Text] |
||||
![]() |
C. Gamby, M. C. Waage, R. G. Allen, and L. Baizer Analysis of the Role of Calmodulin Binding and Sequestration in Neuromodulin (GAP-43) Function J. Biol. Chem., October 25, 1996; 271(43): 26698 - 26705. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Chiaramello, T. Neuman, D. R. Peavy, and M. X. Zuber The GAP-43 Gene Is a Direct Downstream Target of the Basic Helix-Loop-Helix Transcription Factors J. Biol. Chem., September 6, 1996; 271(36): 22035 - 22043. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Gamby, M. C. Waage, R. G. Allen, and L. Baizer Growth-associated Protein-43 (GAP-43) Facilitates Peptide Hormone Secretion in Mouse Anterior Pituitary AtT-20 Cells J. Biol. Chem., April 26, 1996; 271(17): 10023 - 10028. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. M. Strittmatter Signal Transduction at the Neuronal Growth Cone Neuroscientist, March 1, 1996; 2(2): 83 - 86. [Abstract] [PDF] |
||||