Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In many mammalian cells, the transport of newly synthesized or externally added lysosomal enzymes to lysosomes is depend on their specific recognition by receptors for mannose 6-phosphate (Man-6-P). The physiological importance of this pathway was confirmed by the finding that fibroblasts from patients with mucolipidosis type II (ML-II ; I - cell disease) fail to phosphorylate mannose residues on their newly synthesized lysosomal enzymes, which results in the secretion of a large percentage of their acid hydrolases into the culture medium. However, lysosomal enzymes themselves do not contain the any consensus amino acid sequences for acquiring the Man-6-P recognition marker. Kornfeld et al revealed using cathepsin D-pepsinogen chimera proteins that UDP-N-acetylglucosamine: lysosomal enzyme N-acetylglucosamine-1-phosphotransferase recognizes not only oligosaccharides but also the three-dimensional structure of the lysosomal enzymes when transfers N-acetylglucosamine-1-phosphate to lysosomal acid hydrolases.
 ...
PMID:[Lysosomal hydrolases have specific conformational domains for acquisition of mannose-6-phosphate]. 857 31

We compared the processing and presentation of the model Ag, hen-egg white lysozyme (HEL) expressed in C3.F6 APC as a fusion protein to three different acid hydrolases: cathepsin D, to an unglycosylated form of cathepsin D, and to pepsinogen. As expected from the biology of mannose 6-phosphate (Man-6-P)-containing enzyme, cathepsin D-HEL was delivered to the endosomal/lysosomal system. In contrast, the unglycosylated cathepsin D-HEL was retained in ER/Golgi and some was found in lysosomes. Most of pepsinogen-HEL was rapidly secreted from the APC. All transfectants presented HEL epitopes to T cell hybridomas. Regardless of the main route of traffic of the proteins, the strong I-Ak binding epitope HEL 48-62 was well presented by all. The biochemical forms of this epitope were identical for all. Three other epitopes of HEL that bind I-Ak with less affinity were processed equally well by unglycosylated cathepsin D-HEL and HEL-Ld. The glycosylated cathepsin D-HEL was less efficient in generating the 114-129 epitope. Pepsinogen-HEL was the less efficient of all transfectants in presenting these subdominant epitopes. Soluble cathepsin D-HEL recovered from culture supernatant was strongly immunogenic when added to C3.F6. The uptake was inhibited by free Man-6-P, indicating that the surface Man-6-P receptor can effectively deliver proteins to the class II MHC system.
 ...
PMID:Presentation on class II MHC molecules of endogenous lysozyme targeted to the endocytic pathway. 905

The mammalian aspartic proteinases procathepsin D and pepsinogen form insoluble inclusion bodies when expressed in bacteria. They become soluble but nonnative when synthesized as fusions to the carboxy terminus of E. coli maltose-binding protein (MBP). Since these nonnative states of the two aspartic proteinases showed no tendency to form insoluble aggregates, their biophysical properties were analyzed. The MBP portions were properly folded as shown by binding to amylose, but the aspartic proteinase moieties failed to bind pepstatin and lacked enzymatic activity, indicating that they were not correctly folded. When treated with proteinase K, only the MBP portion of the fusions was resistant to proteolysis. The fusion between MBP and cathepsin D had increased hydrophobic surface exposure compared to the two unfused partners, as determined by bis-ANS binding. Ultracentrifugal sedimentation analysis of MBP-procathepsin D and MBP-pepsinogen revealed species with very large and heterogeneous sedimentation values. Refolding of the fusions from 8 M urea generated proteins no larger than dimers. Refolded MBP-pepsinogen was proteolytically active, while only a few percent of renatured MBP-procathepsin D was obtained. The results suggest that MBP-aspartic proteinase fusions can provide a source of soluble but nonnative folding states of the mammalian polypeptides in the absence of aggregation.
 ...
PMID:Properties of soluble fusions between mammalian aspartic proteinases and bacterial maltose-binding protein. 1007 37

Pregnancy-associated glycoproteins (PAGs) isolated from the placenta of various ruminant species are enzymatically inactive members of the aspartic proteinase family. The measurement of these proteins in the maternal blood can be a good indicator of the presence of a live embryo. As certain aspartic proteinases are present in biological fluids in physiological and pathological conditions at various concentrations, it was necessary to determine the specificity of three radioimmunoassay (RIA) systems currently used for the detection of PAG molecules. Commercially available members of the aspartic proteinase family like pepsinogen, pepsin, chymosin, rennet, cathepsin D and renin were tested in a wide concentration range (10 ng/ml - 1 mg/ml). Pepsinogen cross-reacted in RIA 1, RIA 2 and RIA 3 over 1 mg/ml, 50 microg/ml and 500 microg/ml concentrations, respectively. In the presence of pepsin, cross-reaction was observed in RIA 1, RIA 2 and RIA 3 over 1 mg/ml, 500 microg/ml and 1 mg/ml concentrations, respectively. Chymosin and rennet could cross-react in RIA 2 and RIA 3, while renin and cathepsin D did not decrease the binding of the tracer to antisera more, than that of the minimal detection limit. As the plasma/serum concentrations of the examined aspartic proteinases reported in the literature were outside the concentration range where cross-reaction was observed, it can be concluded that these RIA systems were specific for the detection of PAGs in biological fluids.
 ...
PMID:Aspartic proteinase members secreted by the ruminant placenta: specificity of three radioimmunoassay systems for the measurement of pregnancy-associated glycoproteins. 1246 69


<< Previous 1 2 3