TY - JOUR
T1 - Involvement of a membrane-associated serine/threonine kinase complex in cellular binding of visna virus
AU - Barber, S. A.
AU - Bruett, L.
AU - Clements, J. E.
N1 - Funding Information:
The authors would like to thank Debbie Hauer and David Herbst for excellent technical support, Maryann Brooks for preparing the manuscript in publication form, and the rest of the Retrovirus Laboratory for contributing to useful discussions regarding the research presented herein. This work was supported by National Institutes of Health Grants NS07392 and NS23039.
PY - 2000/9/1
Y1 - 2000/9/1
N2 - Previous studies from our laboratory identified cellular membrane proteins that mediate binding of visna virus to susceptible cells. In the pilot report, antiserum raised to one of these proteins, ~45 kDa, was shown to both label the surface of susceptible cells and block the binding of visna virus to cell membranes. In a recent study, we reported that the same antiserum, designated 2-23, significantly inhibited infection by visna virus and specifically immunoprecipitated a membrane-associated protein complex from susceptible cells, comprised of a ~45- kDa protein, as well as a 30-kDa protein. Because the 30-kDa protein was readily detectable in TRANS[35S]-LABELed susceptible cells, we were able to characterize this protein biochemically, as a chondroitin sulfate proteoglycan. In the present study, we sought to characterize the ~45-kDa protein and examined 2-23 immune complexes for the presence of kinase activity. Our data indicate that although in vitro kinase assays of 2-23 immunoprecipitates specifically result in the phosphorylation of the ~45-kDa protein as well as a novel ~56-kDa protein, only the ~45-kDa protein exhibits inherent serine/threonine kinase activity. In addition, the kinase activity can be isolated in 2-23 immunoprecipitates of membranes prepared from visna virus-susceptible cells. Finally, in an effort to evaluate the biological relevance of our in vitro observations, we examined 2-23 immunoprecipitates of [32P]orthophosphate-labeled visna-susceptible cells and report that the ~56-kDa protein is phosphorylated constitutively on serine in vivo. Collectively, these data implicate a serine/threonine kinase complex in the binding/infection of visna virus. (C) 2000 Academic Press.
AB - Previous studies from our laboratory identified cellular membrane proteins that mediate binding of visna virus to susceptible cells. In the pilot report, antiserum raised to one of these proteins, ~45 kDa, was shown to both label the surface of susceptible cells and block the binding of visna virus to cell membranes. In a recent study, we reported that the same antiserum, designated 2-23, significantly inhibited infection by visna virus and specifically immunoprecipitated a membrane-associated protein complex from susceptible cells, comprised of a ~45- kDa protein, as well as a 30-kDa protein. Because the 30-kDa protein was readily detectable in TRANS[35S]-LABELed susceptible cells, we were able to characterize this protein biochemically, as a chondroitin sulfate proteoglycan. In the present study, we sought to characterize the ~45-kDa protein and examined 2-23 immune complexes for the presence of kinase activity. Our data indicate that although in vitro kinase assays of 2-23 immunoprecipitates specifically result in the phosphorylation of the ~45-kDa protein as well as a novel ~56-kDa protein, only the ~45-kDa protein exhibits inherent serine/threonine kinase activity. In addition, the kinase activity can be isolated in 2-23 immunoprecipitates of membranes prepared from visna virus-susceptible cells. Finally, in an effort to evaluate the biological relevance of our in vitro observations, we examined 2-23 immunoprecipitates of [32P]orthophosphate-labeled visna-susceptible cells and report that the ~56-kDa protein is phosphorylated constitutively on serine in vivo. Collectively, these data implicate a serine/threonine kinase complex in the binding/infection of visna virus. (C) 2000 Academic Press.
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U2 - 10.1006/viro.2000.0482
DO - 10.1006/viro.2000.0482
M3 - Article
C2 - 10964775
AN - SCOPUS:0034284598
SN - 0042-6822
VL - 274
SP - 321
EP - 330
JO - Virology
JF - Virology
IS - 2
ER -