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LDLC encodes a brefeldin A-sensitive, peripheral Golgi protein required for normal Golgi function
S D Podos1, P Reddy, J Ashkenas
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
The Journal of Cell Biology
|November 1, 1994
Summary
Researchers identified a new Golgi protein, ldlCp, crucial for multiple Golgi functions. Its association with the Golgi depends on the LDLB gene and brefeldin A, highlighting its role in cellular processes.
Area of Science:
- Cell Biology
- Molecular Genetics
- Glycobiology
Background:
- Low density lipoprotein (LDL) receptor-deficient Chinese hamster ovary (CHO) cell mutants (ldlB, ldlC) display defects in Golgi-associated processes.
- Abnormal glycosylation in these mutants leads to reduced LDL receptor stability and activity.
Purpose of the Study:
- To identify the gene responsible for the ldlC mutant phenotype.
- To characterize the function and localization of the protein encoded by the identified gene.
Main Methods:
- cDNA cloning and sequencing of a human gene (LDLC) that corrects ldlC cell defects.
- Analysis of LDLC mRNA levels in wild-type and mutant cells.
- Protein sequence prediction and comparison.
- Immunofluorescence studies to determine protein localization.
Main Results:
- A human cDNA (LDLC) was cloned and sequenced, correcting ldlC cell defects but not ldlB.
- ldlC cells lack detectable LDLC mRNA, identifying LDLC as the defective gene.
- The predicted protein, ldlCp, is novel, lacking known structural motifs.
- ldlCp is a peripheral Golgi protein, sensitive to brefeldin A.
- In ldlB cells, ldlCp is not associated with the Golgi, indicating LDLB dependence.
Conclusions:
- A previously unrecognized protein, ldlCp, is essential for multiple Golgi functions.
- ldlCp's peripheral association with the Golgi is dependent on the LDLB gene and brefeldin A.
- This discovery provides new insights into Golgi-associated cellular processes and genetic regulation.