title: Activation and function of the Rap1 GTPase in B lymphocytes.
abstract: Rap1 is a monomeric GTPase that is closely related to Ras. In this review, we summarize our recent work showing that the B cell antigen receptor (BCR), as well as chemokine receptors, activate Rap1 via a pathway that involves phospholipase C-dependent production of diacylglycerol (DAG). The possible identities of the DAG-regulated guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) that regulate the activation of Rap1 by the BCR and chemokine receptors will be discussed. Although initially thought to be an antagonist of Ras-mediated signaling, Rap1 does not appear to modulate the ability of the BCR to activate downstream targets of Ras. Instead, activation of Rap1 promotes B cell adhesion as well as B cell migration toward chemokines. Thus, Rap1 may play a key role in a number of processes that are essential for B cell development and activation.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.
authors.forename: S J
authors.initials: SJ
authors.lastname: McLeod
authors.forename: M R
authors.initials: MR
authors.lastname: Gold
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000201:enzymology* / Q000276:immunology* / Q000502:physiology; D002448:Cell Adhesion; D002465:Cell Movement; D004789:Enzyme Activation; D020690:GTPase-Activating Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018448:Models, Immunological; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D015398:Signal Transduction; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D016023:Integrins; D011947:Receptors, Antigen, B-Cell; D020928:Mitogen-Activated Protein Kinases; D020827:rap1 GTP-Binding Proteins