Transient membrane association of the precursors of cathepsin C during their transfer into lysosomes.
Transport of the lysosomal enzyme cathepsin C was studied in Morris hepatoma 7777 cells. Subcellular fractions obtained after isopyenic centrifugation in sucrose gradients of labelled cell homogenates were sequentially extracted by hypo-osmotic shock, Na2CO3 and Triton X-100. Polypeptides related to cathepsin C were immunoprecipitated and analysed by SDS/PAGE and fluorography. At early times after synthesis and for up to 60 min, precursor polypeptides of cathepsin C are distributed in endoplasmic reticulum and Golgi fractions, in membrane-associated form, as Triton X-100 is necessary for their extraction. At 2 h and later after synthesis, intermediate and mature forms of the enzyme can be totally extracted by hypo-osmotic shock from gradient fractions corresponding to the lysosomes of Morris hepatoma 7777 cells.
Burge
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Laboratoire de Chimie Physiologique, Facultés Universitaries Notre Dame de la Paix, Namur, Belgium.
Mainferme
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Wattiaux
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D000818:Animals; D001692:Biological Transport; D020789:Cathepsin C; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D002500:Centrifugation, Isopycnic; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007163:Immunosorbent Techniques; D007700:Kinetics; D008114:Liver Neoplasms, Experimental; D008247:Lysosomes / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D011498:Protein Precursors; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D020789:Cathepsin C