Many eukaryotic cell surface proteins are anchored to the plasma membrane via glycosylphosphatidylinositol (GPI). The GPI transamidase mediates GPI anchoring in the endoplasmic reticulum, by replacing a protein's C-terminal GPI attachment signal peptide with a pre-assembled GPI. During this transamidation reaction, the GPI transamidase forms a carbonyl intermediate with a substrate protein. It was known that the GPI transamidase is a complex containing GAA1 and GPI8. Here, we report two new components of this enzyme: PIG-S and PIG-T. To determine roles for PIG-S and PIG-T, we disrupted these genes in mouse F9 cells by homologous recombination. PIG-S and PIG-T knockout cells were defective in transfer of GPI to proteins, particularly in formation of the carbonyl intermediates. We also demonstrate that PIG-S and PIG-T form a protein complex with GAA1 and GPI8, and that PIG-T maintains the complex by stabilizing the expression of GAA1 and GPI8. Saccharomyces cerevisiae Gpi16p (YHR188C) and Gpi17p (YDR434W) are orthologues of PIG-T and PIG-S, respectively.
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Increase the total number of rows showing on this page using the pull-down located below the table, or use the page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column header to sort by that column; filter the table using the "Filter" box at the top of the table; click on the small "i" buttons located within a cell for an annotation to view further details.
| Gene | Phenotype | Experiment Type | Mutant Information | Strain Background | Chemical | Details |
|---|---|---|---|---|---|---|
| GAA1 | chemical compound accumulation: increased | classical genetics | repressible | S288C | glycosylphosphatidylinositol | Details: accumulation of the complete GPI precursor, relative to wt cells which do not accumulate the precursor |
| GPI8 | chemical compound accumulation: increased | classical genetics | repressible | S288C | glycosylphosphatidylinositol | Details: accumulation of the complete GPI precursor, relative to wt cells which do not accumulate the precursor |
| GPI16 | chemical compound accumulation: increased | classical genetics | repressible | S288C | glycosylphosphatidylinositol | Details: accumulation of the complete GPI precursor, relative to wt cells which do not accumulate the precursor |
| GPI17 | chemical compound accumulation: increased | classical genetics | repressible | S288C | glycosylphosphatidylinositol | Details: accumulation of the complete GPI precursor, relative to wt cells which do not accumulate the precursor |