Lysine residues in the C-terminal lobe and lysosomal targeting of procathepsin D.
A major pathway to the lysosome for soluble hydrolases involves the 6-phosphorylation of mannose residues. The initial step in this reaction is catalyzed by a phosphotransferase which recognizes lysosomal precursors. We constructed mutants of human procathepsin D whose targeting to the lysosome could be assayed directly in intact cells. Eight lysine residues were individually converted to glutamic acid on the surface of the carboxyl terminal lobe of the protein. Mutants with as many as four Lys to Glu mutations were normally targeted to the lysosome and processed to the mature form of the enzyme in transfected cells. We conclude that the C-terminal lobe of procathepsin D may not carry a determinant essential for lysosomal targeting in intact fibroblasts.
Schorey
J S
JS
Research Service, Audie L. Murphy Memorial Veterans Administration Hospital, San Antonio, Texas, USA.
Fortenberry
S C
SC
Chirgwin
J M
JM
D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002402:Cathepsin D / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006031:Glycosylation; D006801:Humans; D008239:Lysine; D008247:Lysosomes / Q000378:metabolism*; D008360:Mannosephosphates / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D012083:Renin / Q000378:metabolism; D013045:Species Specificity
D004792:Enzyme Precursors; D008360:Mannosephosphates; D016271:Proto-Oncogene Proteins c-myc; D011993:Recombinant Fusion Proteins; C027693:mannose-6-phosphate; D010770:Phosphotransferases; C058345:procathepsin D; D012083:Renin; D002402:Cathepsin D; D008239:Lysine