p125 is a novel mammalian Sec23p-interacting protein with structural similarity to phospholipid-modifying proteins.
COPII-coated vesicles are involved in protein transport from the endoplasmic reticulum to the Golgi apparatus. COPII consists of three parts: Sar1p and the two protein complexes, Sec23p-Sec24p and Sec13p-Sec31p. Using a glutathione S-transferase fusion protein with mouse Sec23p, we identified a novel mammalian Sec23p-interacting protein, p125, which is clearly distinct from Sec24p. The N-terminal region of p125 is rich in proline residues, and the central and C-terminal regions exhibit significant homology to phospholipid-modifying proteins, especially phosphatidic acid preferring-phospholipase A1. We transiently expressed p125 and mouse Sec23p in mammalian cells and examined their interaction. The results showed that the N-terminal region of p125 is important for the interaction with Sec23p. We confirmed the interaction between the two proteins by a yeast two-hybrid assay. Overexpression of p125, like that of mammalian Sec23p, caused disorganization of the endoplasmic reticulum-Golgi intermediate compartment and Golgi apparatus, suggesting its role in the early secretory pathway.
School of Life Science, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo 192-0392, Japan.
K
K
Tani
T
T
Mizoguchi
A
A
Iwamatsu
K
K
Hatsuzawa
M
M
Tagaya
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010712:Phosphatidic Acids / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins; D017386:Sequence Homology, Amino Acid; D014709:Vero Cells; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D010712:Phosphatidic Acids; D010743:Phospholipids; D011506:Proteins; D016601:RNA-Binding Proteins; C512739:SEC23A protein, human; C120603:SEC23IP protein, human; C079038:Sec23a protein, mouse; D033921:Vesicular Transport Proteins; D010741:Phospholipases A