Involvement of the penta-EF-hand protein Pef1p in the Ca2+-dependent regulation of COPII subunit assembly in Saccharomyces cerevisiae.
Although it is well established that the coat protein complex II (COPII) mediates the transport of proteins and lipids from the endoplasmic reticulum (ER) to the Golgi apparatus, the regulation of the vesicular transport event and the mechanisms that act to counterbalance the vesicle flow between the ER and Golgi are poorly understood. In this study, we present data indicating that the penta-EF-hand Ca(2+)-binding protein Pef1p directly interacts with the COPII coat subunit Sec31p and regulates COPII assembly in Saccharomyces cerevisiae. ALG-2, a mammalian homolog of Pef1p, has been shown to interact with Sec31A in a Ca(2+)-dependent manner and to have a role in stabilizing the association of the Sec13/31 complex with the membrane. However, Pef1p displayed reversed Ca(2+) dependence for Sec13/31p association; only the Ca(2+)-free form of Pef1p bound to the Sec13/31p complex. In addition, the influence on COPII coat assembly also appeared to be reversed; Pef1p binding acted as a kinetic inhibitor to delay Sec13/31p recruitment. Our results provide further evidence for a linkage between Ca(2+)-dependent signaling and ER-to-Golgi trafficking, but its mechanism of action in yeast seems to be different from the mechanism reported for its mammalian homolog ALG-2.
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan.
Mariko
M
Yoshibori
Tomohiro
T
Yorimitsu
Ken
K
Sato
D000595:Amino Acid Sequence; D001692:Biological Transport; D022181:COP-Coated Vesicles / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D015870:Gene Expression; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D033921:Vesicular Transport Proteins / Q000378:metabolism
D002135:Calcium-Binding Proteins; D046912:Multiprotein Complexes; D028861:Nuclear Pore Complex Proteins; C523635:PEF1 protein, S cerevisiae; C106113:SEC31 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D002118:Calcium