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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
13
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pubmed:dateCreated |
1987-6-5
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pubmed:abstractText |
Our previous studies demonstrated that a site-specific cleavage event initiates the degradation of large premature termination polypeptides of beta-galactosidase in Escherichia coli. We have isolated the first cleavage intermediate, the "B" polypeptide, by elution from sodium dodecyl sulfate-polyacrylamide gels. The NH2 terminus of this protein, determined by automated Edman degradation, was that of the wild-type molecule and thus established that the first cleavage event was at the COOH-terminal end. The sequence of the COOH-terminal end of the B polypeptide was determined by using the enzyme carboxypeptidase Y. Direct assignment of COOH-terminal residues was made by using o-phthaldialdehyde derivatization and the stoichiometry confirmed by a double-label analysis. The COOH-terminal end of the B polypeptide is at position 837 in the beta-galactosidase sequence. If a single endoproteolytic cleavage event was responsible, the cleavage would have occurred between 2 threonine residues (at positions 837 and 838) that are located within a hydrophobic domain. We have observed other covalent modifications that precede the appearance of the B polypeptide, but these do not appear to participate in signaling the first cleavage event. The structure of the COOH-terminal end of B suggests a high degree of specificity by the initial cleavage enzyme. We propose that this unique site serves as a specific signal and that exposure of this site to the specific cleavage enzyme controls the event initiating the degradation pathway.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Carboxypeptidases,
http://linkedlifedata.com/resource/pubmed/chemical/Galactosidases,
http://linkedlifedata.com/resource/pubmed/chemical/Peptides,
http://linkedlifedata.com/resource/pubmed/chemical/beta-Galactosidase,
http://linkedlifedata.com/resource/pubmed/chemical/serine carboxypeptidase
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
5
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pubmed:volume |
262
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
6357-64
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:3106354-Amino Acid Sequence,
pubmed-meshheading:3106354-Carboxypeptidases,
pubmed-meshheading:3106354-Electrophoresis, Polyacrylamide Gel,
pubmed-meshheading:3106354-Escherichia coli,
pubmed-meshheading:3106354-Galactosidases,
pubmed-meshheading:3106354-Peptide Chain Termination, Translational,
pubmed-meshheading:3106354-Peptides,
pubmed-meshheading:3106354-beta-Galactosidase
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pubmed:year |
1987
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pubmed:articleTitle |
Early steps initiating a degradation pathway in Escherichia coli. Characterization of the first intermediate.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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