Klaus C, Guiard B, Neupert W, Brunner M
Institut für Physiologische Chemie der Universität München, München, Germany.
Eur J Biochem. 1996 Mar 15;236(3):856-61. doi: 10.1111/j.1432-1033.1996.00856.x.
Determinants in a mitochondrial targeting signal for import and processing were analyzed by introducing deletions into the presequence of cytochrome b2. The matrix targeting signal and the signal recognized by the mitochondrial processing peptidase were found to be separate. The signal for import into the matrix is located at the N-terminus within a stretch of 20 amino acid residues that has the potential to form a positively charged, amphipathic alpha-helix. The mitochondrial processing peptidase cleaves after residue 31 and recognizes a short sequence motif around the scissile bond. In the context of a presequence, the cleavage site is accessible for the processing peptidase. At a different location or in a different context, the cleavage site motif is still specifically recognized but processed with lower efficiency. The matrix targeting signal may help to present the cleavage site motif to the mitochondrial processing peptidase.
通过对细胞色素b2前序列引入缺失来分析线粒体靶向信号中用于导入和加工的决定因素。发现基质靶向信号和线粒体加工肽酶识别的信号是分开的。导入基质的信号位于N端，在一段20个氨基酸残基内，该残基有可能形成带正电荷的两亲性α-螺旋。线粒体加工肽酶在第31位残基后切割，并识别切割键周围的短序列基序。在前序列的背景下，切割位点对于加工肽酶是可及的。在不同位置或不同背景下，切割位点基序仍能被特异性识别，但加工效率较低。基质靶向信号可能有助于将切割位点基序呈现给线粒体加工肽酶。
