LDLC encodes a brefeldin A-sensitive, peripheral Golgi protein required for normal Golgi function.
Open Access
- 1 November 1994
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 127 (3), 679-691
- https://doi.org/10.1083/jcb.127.3.679
Abstract
Two genetically distinct classes of low density lipoprotein (LDL) receptor-deficient Chinese hamster ovary cell mutants, ldlB and ldlC, exhibit nearly identical pleiotropic defects in multiple medial and trans Golgi-associated processes (Kingsley, D., K. F. Kozarsky, M. Segal, and M. Krieger. 1986. J. Cell Biol. 102:1576-1585). In these mutants, the synthesis of virtually all N- and O-linked glycoproteins and of the major lipid-linked oligosaccharides is abnormal. The abnormal glycosylation of LDL receptors in ldlB and ldlC cells results in their dramatically reduced stability and thus very low LDL receptor activity. We have cloned and sequenced a human cDNA (LDLC) which corrects the mutant phenotypes of ldlC, but not ldlB, cells. Unlike wild-type CHO or ldlB cells, ldlC cells had virtually no detectable endogenous LDLC mRNA, indicating that LDLC is likely to be the normal human homologue of the defective gene in ldlC cells. The predicted sequence of the human LDLC protein (ldlCp, approximately 83 kD) is not similar to that of any known proteins, and contains no major common structural motifs such as transmembrane domains or an ER translocation signal sequence. We have also determined the sequence of the Caenorhabditis elegans ldlCp by cDNA cloning and sequencing. Its similarity to that of human ldlCp suggests that ldlCp mediates a well-conserved cellular function. Immunofluorescence studies with anti-ldlCp antibodies in mammalian cells established that ldlCp is a peripheral Golgi protein whose association with the Golgi is brefeldin A sensitive. In ldlB cells, ldlCp was expressed at normal levels; however, it was not associated with the Golgi. Thus, a combination of somatic cell and molecular genetics has identified a previously unrecognized protein, ldlCp, which is required for multiple Golgi functions and whose peripheral association with the Golgi is both LDLB dependent and brefeldin A sensitive.Keywords
This publication has 60 references indexed in Scilit:
- Disruptions in Golgi structure and membrane traffic in a conditional lethal mammalian cell mutant are corrected by epsilon-COP.The Journal of cell biology, 1994
- Implications of the SNARE hypothesis for intracellular membrane topology and dynamicsCurrent Biology, 1994
- Biochemical dissection of AP-1 recruitment onto Golgi membranes.The Journal of cell biology, 1993
- 'Coatomer': a cytosolic protein complex containing subunits of non-clathrin-coated Golgi transport vesiclesNature, 1991
- A coat subunit of Golgi-derived non-clathrin-coated vesicles with homology to the clathrin-coated vesicle coat protein β-adaptinNature, 1991
- Basic local alignment search toolJournal of Molecular Biology, 1990
- Rapid redistribution of Golgi proteins into the ER in cells treated with brefeldin A: Evidence for membrane cycling from Golgi to ERCell, 1989
- Regulation of Protein Export From the Endoplasmic ReticulumAnnual Review of Cell Biology, 1988
- A microtubule-binding protein associated with membranes of the Golgi apparatus.The Journal of cell biology, 1986
- Isolation of Chinese hamster cell mutants defective in the receptor-mediated endocytosis of low density lipoproteinJournal of Molecular Biology, 1981