2 DISTINCT AND INDEPENDENT MITOCHONDRIAL TARGETING SIGNALS FUNCTION IN THE SORTING OF AN INNER MEMBRANE-PROTEIN, CYTOCHROME C(1)

Citation
I. Arnold et al., 2 DISTINCT AND INDEPENDENT MITOCHONDRIAL TARGETING SIGNALS FUNCTION IN THE SORTING OF AN INNER MEMBRANE-PROTEIN, CYTOCHROME C(1), The Journal of biological chemistry, 273(3), 1998, pp. 1469-1476
Citations number
39
Categorie Soggetti
Biology
ISSN journal
00219258
Volume
273
Issue
3
Year of publication
1998
Pages
1469 - 1476
Database
ISI
SICI code
0021-9258(1998)273:3<1469:2DAIMT>2.0.ZU;2-Y
Abstract
Proteins of the mitochondrial inner membrane display a wide variety of orientations, many spanning the membrane more than once, Some of thes e proteins are synthesized with NH2-terminal cleavable targeting seque nces (presequences) whereas others are targeted to mitochondria via in ternal signals, Here we report that two distinct mitochondrial targeti ng signals can be present in precursors of inner membrane proteins, an NH2-terminal one and a second, internal one, Using cytochrome c(1) as a model protein, we demonstrate that these two mitochondrial targetin g signals operate independently of each other, The internal targeting signal, consisting of a transmembrane segment and a stretch of positiv ely charged amino acid residues directly following it, initially direc ts the translocation of the preprotein into the intermembrane space, I t then inserts into the inner membrane from the intermembrane space si de in a Delta psi-dependent manner and thereby determines the orientat ion the protein attains in the inner membrane, Analysis of a number of other presequence-containing protein of the inner membrane suggest th at they too contain such internal targeting signals.