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POINT MUTATIONS IN THE HYDROPHOBIC C-TERMINAL REGION OF RICIN-A CHAIN INDICATE THAT PRO250 PLAYS A KEY ROLE IN MEMBRANE TRANSLOCATION
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UNSPECIFIED (1995) POINT MUTATIONS IN THE HYDROPHOBIC C-TERMINAL REGION OF RICIN-A CHAIN INDICATE THAT PRO250 PLAYS A KEY ROLE IN MEMBRANE TRANSLOCATION. EUROPEAN JOURNAL OF BIOCHEMISTRY, 232 (2). pp. 458-463. ISSN 0014-2956.
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Abstract
A series of mutations have been made in the carboxyl terminus of ricin A chain, centred on the hydrophobic region between amino acid residues Val245 and Val256. The mutant ricin A chains were expressed to a high level in an Escherichia coli system and the proteins purified to homogeneity. The enzymic activity of each of these A chain molecules was tested on rabbit reticulocyte ribosomes; in all cases, the activities were found to be comparable to wild-type recombinant ricin A chain. Following reassociation of these A chains to ricin B chain. Vero cells were challenged with these holotoxins and the cytotoxicities determined. Mutant ricin A chain with Ile247-->Ala was unable to reassociate and form holotoxin, indicating the importance of this residue in the interaction with ricin B chain. Mutant ricin A chain with Pro250-->Ala readily reassociated with ricin B chain, forming holotoxin with a 170-fold reduction in cytotoxicity to Vero cells. Other mutations in this region also produced A chain proteins which gave marked reductions in holotoxin cytotoxicity, We propose therefore that the C-terminal hydrophobic region of ricin A chain may be involved in membrane interactions prior to the translocation of this subunit into the cytosol, and that Pro250 plays a key role in one or both of these steps.
Item Type: | Journal Article | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Journal or Publication Title: | EUROPEAN JOURNAL OF BIOCHEMISTRY | ||||
Publisher: | SPRINGER VERLAG | ||||
ISSN: | 0014-2956 | ||||
Official Date: | 1 September 1995 | ||||
Dates: |
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Volume: | 232 | ||||
Number: | 2 | ||||
Number of Pages: | 6 | ||||
Page Range: | pp. 458-463 | ||||
Publication Status: | Published |
Data sourced from Thomson Reuters' Web of Knowledge
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