Expression of 60 kDa heat shock protein (Hsp60) on plasma membrane of Daudi cells

Abstract

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.

Elevated sodium leads to the increased expression of HSP60 and induces apoptosis in HUVECs

“…We have previously also shown HSP60 on the surface using the monoclonal antibody II-13 [68], originally developed by Singh and Gupta [69], which recognizes the amino acids 288–366, that are highly conserved and located in the center region of the protein. Others have shown HSP60 on the surface of Daudi cells, using antibodies towards both the N and C terminal portions of the protein [70]. Collectively, these results indicate that the intact HSP60 protein appears on the plasma membrane.…”

S-layer, Surface-Accessible, and Concanavalin A Binding Proteins of Methanosarcina acetivorans and Methanosarcina mazei

“…, 60 kDa heat shock proteins and GroEL), are known to be present on eukaryotic and bacterial cell surfaces, in addition to their primary cytosolic localization 22,24,59-62. Increased amounts of Hsp60 are also observed on the surfaces of stressed cells 63-68.…”

Association of heat shock proteins and neuronal membrane components with lipid rafts from the rat brain

“…Hsp40 is closely associated with Hsc70 and is considered as a cochaperone of Hsc70 in the process of protein folding (Ohtsuka and Hata, 2000). A range of Hsps localizes to the cell membrane (Arispe and De Maio, 2000; Kovar et al, 2004; Cicconi et al, 2004). In the brain, Hsp90, Hsc70, and Hsp60 are found in a synaptic membrane fraction isolated by biochemical methods (Bechtold et al, 2000).…”