1,721,008 research outputs found
Human and hamster procathepsin D, although equally tagged with mannose-6-phosphate, are differentially targeted to lysosomes in transfected BHK cells
No full textEnzymatic phosphorylation of lysosomal enzymes in the presence of UDP-N-acetylglucosamine. Absence of the activity in I-cell fibroblasts
No full textSummary: Recent finding of a-N-ocetylglucosamine( I)phospho(6)mannose diesters in lysosomal enzymes suggested that formation of monnose 6-phosphate residues involves transfer of N-acetylglucosamine l- hos hote to mannose. Using dephosphorylated R-hexosaminidase as acceptor and F t3-3 “I P UDP-N-acetylglucosamine OS donor for the phosphate group, phosphorylation of R-hexosaminidose by microsomes from rot liver, humon placenta and human skin fibroblosts wos achieved. The reaction was not affected by tunicomycin. Acid hydrolysis released monnose 6-[32P] phosphate from the phosphorylated l3-hexosaminidase. Our results suggest that lysosomal enzymes are phosphorylated by tronsfer of N-acetylglucosamine l-phosphate from UDP-N-ocetylglucosamine. The transferose activity wos deficient in fibroblasts from patients affected with l-cell disease. This deficiency is proposed to be the primary enzyme defect in I-ccl I disease
Mis-sorting of procathepsin D in metastogenic tumor cells is not due to impaired synthesis of the phosphomannosyl signal
No full textEFFECT OF AMMONIUM-CHLORIDE ON THE FORMATION OF PHOSPHOMONOESTER GROUPS IN CATHEPSIN-D IN U937 CELLS
No full textLysosomal segregation of a mannose-rich glycoprotein imparted by the prosequence of myeloperoxidase
No full textDETERMINATION OF THE PHOSPHORYLATION, UNCOVERING OF MANNOSE 6-PHOSPHATE GROUPS AND TARGETING OF LYSOSOMAL-ENZYMES
No full textThere are at least three stages in the targeting of soluble lysosomal enzymes: transfer of N-acetylglucosaminyl 1-phosphate to high-mannose oligosaccharide side chains, removal of N-acetylglucosamine and recognition of the "uncovered" mannose 6-phosphate residues. Defects in the transfer reaction cause mucolipidoses II and III. Those in the subsequent stages of the targeting may result in similar clinical disorders. To differentiate between possible defects of the targeting in cultured cells we have developed a procedure for a combined detection of the phosphorylation, uncovering of the transferred phosphate residues and the targeting of lysosomal enzymes. For this purpose cultured cells are metabolically labelled with [32P]phosphate and a lysosomal enzyme, such as cathepsin D, is isolated from the labelled cells and the medium by immunoprecipitation. The immunoprecipitates are dissolved with sodium dodecylsulphate and incubated in the presence and absence of calf intestine alkaline phosphatase. We show that the treatment of the denatured protein results in hydrolysis of phosphomonoester groups and that the phosphodiester and the peptide bonds remain intact. The initial and the residual radioactivity associated with the lysosomal enzyme which represent the total phosphate and the phosphodiester groups, respectively, are determined by gel-electrophoresis, fluorography and densitometry. This procedure extends one of the previously established methods for the diagnosis of mucolipidoses II and III
DIFFERENTIAL SEGREGATION OF HUMAN AND HAMSTER CATHEPSIN-D IN TRANSFECTED BABY-HAMSTER KIDNEY-CELLS
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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