SECRETORY GRANULES IN THE CYTOPLASM OF A WALL-LESS MUTANT OF CHLAMYDOMONAS-REINHARDTII CONTAIN PROCESSED LIGHT-HARVESTING COMPLEX APOPROTEINS AND HSP70

Large, electron dense granules are present within vacuoles in the cyto plasm of Chlamydomonas reinhardtii cw15arg7A cells. Immunocytochemical electron microscopy revealed labeling of these granules when sections of cells were incubated with antibodies specific for apoproteins (Lhc b) of the light-harvesting chlorophyll a/b complex (LHCII). The granul es were also labeled with antibodies against the cytosolic molecular c haperone Hsp70. Purified granules contained Hsp70 and processed, matur e forms of Lhcb as minor constituents. Appearance of processed Lhcb in the vacuole suggests that these proteins were products of retrograde movement resulting from aborted import into the chloroplast. Immunorea ctive granules were released from the cell following fusion of the vac uolar and plasma membranes.