TY - JOUR
T1 - Expression of 60 kDa heat shock protein (Hsp60) on plasma membrane of Daudi cells
AU - Cicconi, Rosella
AU - Delpino, Andrea
AU - Piselli, Pierluca
AU - Castelli, Mauro
AU - Vismara, Daniela
PY - 2004/4
Y1 - 2004/4
N2 - In Daudi cells, a fraction of the 60 kDa heat shock protein (Hsp60), which is typically a mitochondrial protein, is located on cell membrane. This was demonstrated by the recovery of biotinylated Hsp60 in the anti-Hsp60 immunoprecipitate obtained from cells in which surface-exposed proteins were selectively labeled with biotin. In further experiments, isolated membrane proteins (obtained by two different biochemical methods) were probed in Western blot with two antibodies (N-20 and K-19) directed against different epitopes located, respectively, at the amino- and at the carboxyl-terminus of the Hsp60. Both these antibodies recognized, among the isolated membrane proteins, a unique band with an electrophoretic mobility identical to that of the cytoplasmic Hsp60, thus demonstrating that Hsp60 is present on cell surface as an intact, full-length, protein. FACS analysis, performed with the same two highly specific anti-Hsp60 antibodies, confirmed that both the N-terminus and the C-terminus of the Hsp60 are exposed outside the cell and are accessible for recognition by the corresponding antibody. Moreover, quantitative analysis of the data showed that constitutive cell surface expression of the Hsp60 is limited to a small fraction (about 10%) of the whole cell population.
AB - In Daudi cells, a fraction of the 60 kDa heat shock protein (Hsp60), which is typically a mitochondrial protein, is located on cell membrane. This was demonstrated by the recovery of biotinylated Hsp60 in the anti-Hsp60 immunoprecipitate obtained from cells in which surface-exposed proteins were selectively labeled with biotin. In further experiments, isolated membrane proteins (obtained by two different biochemical methods) were probed in Western blot with two antibodies (N-20 and K-19) directed against different epitopes located, respectively, at the amino- and at the carboxyl-terminus of the Hsp60. Both these antibodies recognized, among the isolated membrane proteins, a unique band with an electrophoretic mobility identical to that of the cytoplasmic Hsp60, thus demonstrating that Hsp60 is present on cell surface as an intact, full-length, protein. FACS analysis, performed with the same two highly specific anti-Hsp60 antibodies, confirmed that both the N-terminus and the C-terminus of the Hsp60 are exposed outside the cell and are accessible for recognition by the corresponding antibody. Moreover, quantitative analysis of the data showed that constitutive cell surface expression of the Hsp60 is limited to a small fraction (about 10%) of the whole cell population.
KW - Daudi cells
KW - Hsp60
KW - Membrane expression of Hsps
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U2 - 10.1023/B:MCBI.0000021335.52162.51
DO - 10.1023/B:MCBI.0000021335.52162.51
M3 - Article
C2 - 15124901
AN - SCOPUS:1942474646
VL - 259
SP - 1
EP - 7
JO - Molecular and Cellular Biochemistry
JF - Molecular and Cellular Biochemistry
SN - 0300-8177
IS - 1-2
ER -