Premium
Alternatively spliced forms of the P180 ribosome receptor differ in their ability to induce the proliferation of rough endoplasmic reticulum
Author(s) -
Bai JiZhong,
Leung Euphemia,
Holloway Hilary,
Krissansen Geoffrey W.
Publication year - 2008
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1016/j.cellbi.2007.10.002
Subject(s) - endoplasmic reticulum , secretion , biology , calreticulin , microbiology and biotechnology , secretory protein , ribosome biogenesis , calnexin , ribosome , tandem repeat , biochemistry , rna , gene , genome
Expression of the canine 180‐kDa ribosome receptor p180 in yeast induces the synthesis of RER, and increases the mRNAs of secretory pathway proteins, and protein secretion. To assess whether p180 is a master regulator of cell secretion in mammalian cells, we stably expressed red fluorescent forms of the human p180 variants p180ΔR (no tandem repeats), p180R (26 repeats), and full‐length p180FR (54 repeats) containing different lengths of the tandem repeat ribosome‐binding domain in rat pancreatic RINm5F islet β‐cells. All three fluorescent p180 variants localized exclusively to the RER. Cells transfected with p180R were filled with ribosome‐studded karmellae, whereas p180ΔR and p180FR transfectants contained only increased amounts of mostly smooth ER. Unlike in yeast, over‐expression of p180R failed to increase the secretory pathway proteins calnexin, SEC61β, and calreticulin, or ribosome biogenesis. The data suggest that alternative splicing of the p180 tandem repeat domain is a means of regulating the ribosome‐binding activity of p180, and potentially the secretory activity of the cell. However, p180 is not a master regulator of mammalian cell secretion as it does not concomitantly trigger the synthesis of protein machinery required to enhance protein synthesis and cell secretion.