CELL-SURFACE LOCALIZATION OF THE 60 KDA HEAT-SHOCK CHAPERONIN PROTEIN(HSP60) IN MAMMALIAN-CELLS

To investigate whether the 60-kDa heat shock chaperonin protein (hsp60 ) is present on the surface of mammalian cells, we used immunogold lab eling of intact cells and backscattered electron imaging to image gold particles. Chinese hamster ovary cells and the human leukemic CD4-pos itive T-cell line CEM-SS on glass coverslips were labeled using affini ty-purified monoclonal and polyclonal antibodies specific for hsp60 an d 30 nm gold markers. Cells were imaged using the scanning mode of the conventional transmission electron microscope. Backscattered electron imaging provided definitive identification of the gold markers while secondary electron imaging gave information on surface architecture. L abeling intensity was 250-800 gold particles per cell in Chinese hamst er ovary cells and 600-2000 in CEM-SS human lymphoblasts. The finding of hsp60 on the cell surface of mammalian cells may signify chaperone involvement in surface functions. (C) 1997 Academic Press Limited.