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Role Of Sec61alpha In The Regulated Transfer Of The Ribosome-Nascent Chain Complex From The Signal Recognition Particle To The Translocation Channel, Weiqun Song, David Raden, Elisabet Mandon, Reid Gilmore
Role Of Sec61alpha In The Regulated Transfer Of The Ribosome-Nascent Chain Complex From The Signal Recognition Particle To The Translocation Channel, Weiqun Song, David Raden, Elisabet Mandon, Reid Gilmore
Elisabet Mandon
Targeting of ribosome-nascent chain complexes to the translocon in the endoplasmic reticulum is mediated by the concerted action of the signal recognition particle (SRP) and the SRP receptor (SR). Ribosome-stripped microsomes were digested with proteases to sever cytoplasmic domains of SRalpha, SRbeta, TRAM, and the Sec61 complex. We characterized protein translocation intermediates that accumulate when Sec61alpha or SRbeta is inactivated by proteolysis. In the absence of a functional Sec61 complex, dissociation of SRP54 from the signal sequence is blocked. Experiments using SR proteoliposomes confirmed the assembly of a membrane-bound posttargeting intermediate. These results strongly suggest that the Sec61 complex regulates …
A Mutant Yeast Deficient In Golgi Transport Of Uridine Diphosphate N-Acetylglucosamine, Claudia Abeijon, Elisabet Mandon, Phillips Robbins, Carlos Hirschberg
A Mutant Yeast Deficient In Golgi Transport Of Uridine Diphosphate N-Acetylglucosamine, Claudia Abeijon, Elisabet Mandon, Phillips Robbins, Carlos Hirschberg
Elisabet Mandon
Mannan chains of Kluyveromyces lactis mannoproteins are similar to those of Saccharomyces cerevisiae except that they have terminal alpha1-->2-linked N-acetylglucosamine and lack mannose phosphate. In a previous study, Douglas and Ballou (Douglas, R. K., and Ballou, C. E. (1982) Biochemistry 21, 1561-1570) characterized a mutant, mnn2-2, which lacked terminal N-acetylglucosamine in its mannoproteins. The mutant had normal levels of N-acetylglucosaminyltransferase activity, and the partially purified enzyme from wild-type and mutant cells had the same apparent size, heat stability, affinity for substrates, metal requirement, and subcellular location. No qualitative or quantitative differences were found between mutant and wild-type cells in …