ISSN:
1432-1955
Keywords:
Abbreviationsaa Amino acids
;
BFA brefeldin A
;
bp base pairs
;
ER endoplasmic reticulum
;
FCS fetal calf serum
;
HEPES N-(2-5hydroxyethyl)piperazine-N′- (2-ethanesulfonic acid)
;
mAb(s) monoclonal antibodies
;
NP-40 Nonidet P-40
;
ORF open reading frame
;
pSM/1.6 plasmid carrying the cDNA insert
;
SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electro- phoresis
;
SRP signal recognition particle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The cDNA clone pSM/1.6 encoding the 26.5-kDa precursor molecule of the 16/17-kDa microneme antigen of Sarcocystis muris cyst merozoites was expressed in a cell-free translation/translocation system to study translocation of the protein across membranes. The antigen was found to be translocated across heterologous endoplasmic reticulum membranes. Translocation was accompanied by cleavage of a signal peptide to create a 23-kDa polypeptide that was completely protected from digestion with proteinase K. Pulse-chase analysis of [35S]-methionine-labeled S. muris cyst merozoites demonstrated that the 16/17-kDa antigen derived from a 23-kDa precursor molecule and that its processing occurred at between a few minutes and 2 h after biosynthesis. This leads to the conclusion that the native microneme antigen is secreted from the parasite cell via the endoplasmic reticulum. Sorting into micronemes might occur during transition through a Golgi-like structure, involving cleavage of the hydrophilic propeptide to create the mature 16/17-kDa protein.
Type of Medium:
Electronic Resource
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