Year: 2001
Type: article
Abstract: The paper by Movileanu et al. 2001 in this issue of The Journal describes a test of the applicability of the substituted-cysteine-accessibility method (SCAM; Akabas et al. 1992; Akabas et al. 1994) to the problem of locating the narrowest region of a channel lumen. Movileanu et al. 2001 use unusually large sulfhydryl-directed reagents to probe the wide bore channel formed by Staphylococcal α-hemolysin. The structure of the membrane-associated form of this protein has been solved to high resolution (Song et al. 1996). It is a mushroom-shaped heptameric complex that inserts in the membrane of a susceptible cell with the wide cap on the extracellular side, or on the cis side of an artificial planar lipid membrane, and with the stem traversing the bilayer (see Figure 1 in Movileanu et al. 2001). The entrance to the pore at the extracellular or cis end is 30 A wide. The pore immediately narrows to ∼20 A, and then widens into a large vestibule 46 A across. The pore again narrows to ∼16 A, its major constriction, and then continues to its intracellular or trans end as an irregular cylinder, which is roughly 20 A wide. Bayley and co-workers (Movileanu et al. 2001) demonstrate that they can locate the narrowest constriction of the pore by applying SCAM with large enough reagents.
Author: Arthur Karlin
Institution: Columbia University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W1984442142