A conserved proline-rich region of the Saccharomyces cerevisiae cyclase-associated protein binds SH3 domains and modulates cytoskeletal localization.
Saccharomyces cerevisiae cyclase-associated protein (CAP or Srv2p) is multifunctional. The N-terminal third of CAP binds to adenylyl cyclase and has been implicated in adenylyl cyclase activation in vivo. The widely conserved C-terminal domain of CAP binds to monomeric actin and serves an important cytoskeletal regulatory function in vivo. In addition, all CAP homologs contain a centrally located proline-rich region which has no previously identified function. Recently, SH3 (Src homology 3) domains were shown to bind to proline-rich regions of proteins. Here we report that the proline-rich region of CAP is recognized by the SH3 domains of several proteins, including the yeast actin-associated protein Abp1p. Immunolocalization experiments demonstrate that CAP colocalizes with cortical actin-containing structures in vivo and that a region of CAP containing the SH3 domain binding site is required for this localization. We also demonstrate that the SH3 domain of yeast Abp1p and that of the yeast RAS protein guanine nucleotide exchange factor Cdc25p complex with adenylyl cyclase in vitro. Interestingly, the binding of the Cdc25p SH3 domain is not mediated by CAP and therefore may involve direct binding to adenylyl cyclase or to an unidentified protein which complexes with adenylyl cyclase. We also found that CAP homologous from Schizosaccharomyces pombe and humans bind SH3 domains. The human protein binds most strongly to the SH3 domain from the abl proto-oncogene. These observations identify CAP as an SH3 domain-binding protein and suggest that CAP mediates interactions between SH3 domain proteins and monomeric actin.
Freeman
N L
NL
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Lila
T
T
Mintzer
K A
KA
Chen
Z
Z
Pahk
A J
AJ
Ren
R
R
Drubin
D G
DG
Field
J
J
D048868:Adaptor Proteins, Signal Transducing; D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D002451:Cell Compartmentation; D018797:Cell Cycle Proteins; D017124:Conserved Sequence; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000502:physiology*; D004252:DNA Mutational Analysis; D029721:Drosophila Proteins; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D011392:Proline; D011485:Protein Binding; D000090063:Proto-Oncogene Mas; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D013045:Species Specificity; D018909:src Homology Domains
C062612:ABP1 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; C489549:CAP1 protein, human; C410502:Capt protein, Drosophila; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D005656:Fungal Proteins; C000715470:MAS1 protein, human; D008840:Microfilament Proteins; D000090063:Proto-Oncogene Mas; C073751:SRV2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D011392:Proline; D000262:Adenylyl Cyclases