Abstract
During an examination of in vitro phosphorylation of the adipocyte lipid-binding protein (ALBP) by the insulin receptor, we detected insulin receptor-independent, chemical phosphorylation of ALBP. This activity was present in ALBP purified to homogeneity from murine 3T3-L1 cells and in recombinant murine ALBP purified from expressing E. coli cultures. Phosphoamino acid analysis revealed that chemical phosphorylation of ALBP occurred primarily on Ser residues. The phosphorylation activity occurred in the alkaline pH range from 8 to 11 and exhibited a broad temperature dependence. The reaction rate was linearly dependent upon the ATP concentration and exhibited a biphasic kinetic profile. Eight of twelve other proteins tested also underwent chemical phosphorylation. Zn+2, Mg+2, or Mn+2 promoted optimal phosphorylation of different proteins. We conclude that many proteins are capable of undergoing chemical phosphorylation.
Original language | English (US) |
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Pages (from-to) | 64-71 |
Number of pages | 8 |
Journal | Biochemical and Biophysical Research Communications |
Volume | 163 |
Issue number | 1 |
DOIs | |
State | Published - Aug 30 1989 |
Bibliographical note
Funding Information:We thank P. Lampe for his help with the phosphoaminoa cid analysisa nd A. Smith for her help with cell culture. Funding for this work was provided by grant DK 36979 from the National Institutes of Health and a PresidentialY oung Investigator Award to DAB.