1988 Fiscal Year Final Research Report Summary

Phospholipase Activity in Protein Transport into Mitochondria

Research Project

Project/Area Number	62580149
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	代謝生物化学
Research Institution	Faculty of Medicine, Osaka University
Principal Investigator	YOSHIDA Yukuo Faculty of Medicine, Osaka University, Assistant, 医学部, 助手 (10144453)
Project Period (FY)	1987 – 1988
Keywords	Mitochondria / Protein Transport / Precusor Proteins / ATPaseインヒビター / 15K安定化因子
Research Abstract	Mitochondrial import of an intrinsic ATPase inhibitor and two stabilizing factors, 9K and 15K proteins was investigated. From nucleotide sequences of their genes, the inhibitor and 9K protein were found to have amino terminal presequences as the signals to be targetted by the organelle, while 15K protein had an intramolecular signal but no cleavable presequence. A chemically synthesized presequence of ATPase inhibitor gave rise to transient uncoupling of mitochondrial oxidative phosphorylation. Similar uncoupling was observed with 15K protein denatured by heating in 7M urea, but not with the native protein. During the uncoupling the denatured 15K protein was transported into mitochondria. The uncoupling was blocked by DCCD, but not by olgomycin or atrctyloside. These results suggest that the signal sequence interacts with mitochondrial receptor resulting in opening a H^+ channel and that H^+ influx couples to protein transport into mitochondria.