Identification of an 11-kDa FKBP12-rapamycin-binding domain within the 289-kDa FKBP12-rapamycin-associated protein and characterization of a critical serine residue.

Proc Natl Acad Sci U S A
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Abstract

Complexed with its intracellular receptor, FKBP12, the natural product rapamycin inhibits G1 progression of the cell cycle in a variety of mammalian cell lines and in the yeast Saccharomyces cerevisae. Previously, a mammalian protein that directly associates with FKBP12-rapamycin has been identified and its encoding gene has been cloned from both human (designated FRAP) [Brown, E.J., Albers, M.W., Shin, T.B., Ichikawa, K., Keith, C.T., Lane, W.S. & Schreiber, S.L. (1994) Nature (London) 369, 756-758] and rat (designated RAFT) [Sabatini, D.M., Erdjument-Bromage, H., Lui, M., Tempst, P. & Snyder, S.H. (1994) Cell 78, 35-43]. The full-length FRAP is a 289-kDa protein containing a putative phosphatidylinositol kinase domain. Using an in vitro transcription/translation assay method coupled with proteolysis studies, we have identified an 11-kDa FKBP12-rapamycin-binding domain within FRAP. This minimal binding domain lies N-terminal to the kinase domain and spans residues 2025-2114. In addition, we have carried out mutagenesis studies to investigate the role of Ser2035, a potential phosphorylation site for protein kinase C within this domain. We now show that the FRAP Ser2035-->Ala mutant displays similar binding affinity when compared with the wild-type protein, whereas all other mutations at this site, including mimics of phosphoserine, abolish binding, presumably due to either unfavorable steric interactions or induced conformational changes.

Year of Publication
1995
Journal
Proc Natl Acad Sci U S A
Volume
92
Issue
11
Pages
4947-51
Date Published
1995 May 23
ISSN
0027-8424
PubMed ID
7539137
PubMed Central ID
PMC41824
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Grant list
GM38627 / GM / NIGMS NIH HHS / United States