ISSN:
1573-6881
Keywords:
Mitochondrial channels
;
mitochondrial targeting sequences
;
electron microscopy
;
computer image processing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Membrane crystals of the mitochondrial outer membrane channel VDAC (porin) fromNeurospora crassa were incubated with a 20-amino-acid synthetic peptide corresponding to the N-terminal targeting region of subunit IV of cytochrome oxidase. The peptide caused disordering and contraction of the crystal lattice of the membrane arrays. Also, new stain-excluding features were observed on the peptide-treated arrays which most likely correspond to sites at which the peptide accumulates. The stain exclusion zones associated with binding of the targeting peptide (and with binding of apocytochromec in an earlier study) have been localized on a two-dimensional density map of frozen-hydrated, crystalline VDAC previously obtained by cryo-electron microscopy. The results indicate that both the peptide and cytochromec bind to protein “arms” which extend laterally between the channel lumens. The finding that imported polypeptides bind to a specific region of the VDAC protein implicates this channel in the process by which precursor proteins are recognized at and translocated across the mitochondrial outer membrane.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00769531
Permalink