A late golgi sorting function for Saccharomyces cerevisiae Apmlp, but not for Apm2p, a second yeast clathrin AP medium chain-related protein

J. David Stepp, Alexandra Pellicena-Palle, Scott Hamilton, Tomas Kirchhausen, Sandra K. Lemmon

Research output: Contribution to journalArticle

71 Scopus citations

Abstract

Mammalian clathrin-associated protein (AP) complexes, AP-1 (trans-Golgi network) and AP-2 (plasma membrane), are composed of two large subunits of 91-107 kDa, one medium chain (μ) of 47-50 kDa and one small chain (σ) of 17-19 kDa. Two yeast genes, APM1 and APM2, have been identified that encode proteins related to AP μ chains. APM1, whose sequence was reported previously, codes for a protein of 54 kDa that has greatest similarity to the mammalian 47-kDa μ1 chain of AP-1. APM2 encodes an AP medium chain-related protein of 605 amino acids (predicted molecular weight of 70 kDa) that is only 30-33% identical to the other family members. In yeast containing a normal clathrin heavy chain gene (CHC1), disruptions of the APM genes, singly or in combination, had no detectable phenotypic consequences. However, deletion of APM1 greatly enhanced the temperature-sensitive growth phenotype and the α-factor processing defect displayed by cells carrying a temperature-sensitive allele of the clathrin heavy chain gene. In contrast, deletion of APM1 caused no synthetic phenotypes with clathrin mutants. Biochemical analysis indicated that Apmlp and Apm2p are components of distinct high molecular weight complexes. Apmlp, Apm2p, and clathrin cofractionated in a discrete vesicle population, and the association of Apmlp with the vesicles was disrupted in CHC1 deletion strains. These results suggest that Apmlp is a component of an AP-1-like complex that participates with clathrin in sorting at the trans-Golgi in yeast. We propose that Apm2p represents a new class of AP-medium chain-related proteins that may be involved in a nonclathrin-mediated vesicular transport process in eukaryotic cells.

Original languageEnglish (US)
Pages (from-to)41-58
Number of pages18
JournalMolecular biology of the cell
Volume6
Issue number1
DOIs
StatePublished - Jan 1995

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'A late golgi sorting function for Saccharomyces cerevisiae Apmlp, but not for Apm2p, a second yeast clathrin AP medium chain-related protein'. Together they form a unique fingerprint.

  • Cite this