KAR2, a karyogamy gene, is the yeast homolog of the mammalian BiP/GRP78 gene.
The yeast KAR2 gene was isolated by complementation of a mutation that blocks nuclear fusion. The predicted KAR2 protein sequence is most homologous to mammalian BiP/GRP78 and has several structural features in common with it: a functional secretory signal sequence, a yeast endoplasmic reticulum retention signal (HDEL) at the carboxyl terminus, and the absence of potential N-linked glycosylation sites. Moreover KAR2 is regulated like BiP/GRP78: the level of mRNA is increased by drug treatments and mutations that cause accumulation of secretory precursors in the endoplasmic reticulum. However, unlike BiP/GRP78, KAR2 is also regulated by heat shock. Deletion of the KAR2 gene generated a recessive lethal mutation, showing that BiP/GRP78 function is required for cell viability.
Rose
M D
MD
Department of Biology, Lewis Thomas Laboratory, Princeton University, New Jersey 08544-1014.
Misra
L M
LM
Vogel
J P
JP
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D002467:Cell Nucleus / Q000502:physiology*; D002874:Chromosome Mapping; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000502:physiology*; D005786:Gene Expression Regulation; D005800:Genes, Fungal; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000502:physiology*; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D005810:Multigene Family; D009685:Nuclear Envelope / Q000502:physiology; D021382:Protein Sorting Signals / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000502:physiology*
D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C060153:KAR2 protein, yeast; D021382:Protein Sorting Signals