Kinetics of a novel cytosolic protein during the onset of renal epithelial cell growth.
Exposure of monkey kidney epithelial cells (BSC-1 line) to medium with a reduced K concentration (3.2 mM) stimulated growth and transiently activated glyceraldehyde-3-phosphate dehydrogenase (G3PD). The increase in enzyme activity was mediated by a cytosolic modifier protein that was purified using affinity and size-exclusion chromatography, and anion-exchange high-performance liquid chromatography. The apparent molecular mass of the protein was 62 kDa. A monospecific antibody to the protein was prepared from rabbit antiserum and used as an immunoprobe. Immunocytochemical staining and Western blotting revealed that the protein was a normal constituent of the cytosol and that it accumulated in cells exposed to low-K medium. A quantitative enzyme-linked immunosorbent assay showed that the amount of modifier protein increased progressively for up to 2 h in cells exposed to low-K medium, and then returned to the control value, a kinetic profile similar to that observed for G3PD activity. These results indicate that the modifier protein is a constituent of renal epithelial cells and accumulates transiently in the cytosol where it could regulate G3PD activity during the onset of growth induced by the low-K mitogenic signal.
Aithal
H N
HN
Department of Medicine, University of Chicago, Illinois 60637.
Walsh-Reitz
M M
MM
Kartha
S
S
Gluck
S L
SL
Franklin
W A
WA
Knigge
K M
KM
Toback
F G
FG
D000818:Animals; D015153:Blotting, Western; D002455:Cell Division; D002460:Cell Line; D002522:Chlorocebus aethiops; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D007150:Immunohistochemistry; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D011188:Potassium / Q000502:physiology; D011506:Proteins / Q000032:analysis / Q000378:metabolism*
D011506:Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D011188:Potassium