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Length of ‘matrix-targeting signals’ (MTSs), presequences both necessary and sufficient for mitochondrial targeting

Range	20-60 amino acid residues
Organism	Mitochondria
Reference	Herrmann JM, Neupert W. Protein transport into mitochondria. Curr Opin Microbiol. 2000 Apr3(2):210-4. p.210 right column top paragraphPubMed ID10744987
Primary Source	[5] G. Von Heijne Mitochondrial targeting sequences may form amphiphilic helices EMBO J, 5 (1986), pp. 1335–1342 [6] D. Roise, F. Theiler, S.J. Horvath, J.M. Tomich, J.H. Richards, D.S. Allison, G. Schatz Amphiphilicity is essential for mitochondrial presequence function EMBO J, 7 (1988), pp. 649–653PubMed ID3015599, 3396537
Comments	P.210 right column top paragraph: "Proteins destined to be imported into mitochondria (preproteins) are typically synthesised as precursors carrying amino-terminal extensions. These presequences are both necessary and sufficient for mitochondrial targeting [ref 4] and usually are proteolytically removed following translocation into the matrix. These ‘matrix-targeting signals’ (MTSs) comprise some 20 to 60 amino acid residues that have the potential to form amphiphilic α-helices with one hydrophobic and one positively charged face [primary sources]. The extent of helicity, hydrophobicity and positive charge varies significantly among different presequences and may have to be balanced in vivo to minimise nonspecific membrane binding [ref 7]. Although MTSs are usually found at the amino terminus of preproteins, other arrangements have been described recently: the mitochondrial DNA-helicase Hmi1 has a cleavable carboxy-terminal MTS, which mediates import in a reverse carboxy- to amino-terminal direction [ref 8]."
Entered by	Uri M
ID	113209