The group-specific protein reagents, N-bromacetamide (NBA) and N-bromosuccinimide (NBS), modify sodium channel gating when perfused inside squid axons. The normal fast inactivation of sodium channels is irreversibly destroyed by 1 mM NBA or NBS near neutral pH. NBA apparently exhibits an all-or-none destruction of the inactivation process at the single channel level in a manner similar to internal perfusion of Pronase. Despite the complete removal of inactivation by NBA, the voltage-dependent activation of sodium channels remains unaltered as determined by (a) sodium current turn-on kinetics, (b) sodium tail current kinetics, (c) voltage dependence of steady-state activation, and (d) sensitivity of sodium channels to external calcium concentration. NBA and NBS, which can cleave peptide bonds only at tryptophan, tyrosine, or histidine residues and can oxidize sulfur-containing amino acids, were directly compared with regard to effects on sodium inactivation to several other reagents exhibiting overlapping protein reactivity spectra. N-acetylimidazole, a tyrosine-specific reagent, was the only other compound examined capable of partially mimicking NBA. Our results are consistent with recent models of sodium inactivation and support the involvement of a tyrosine residue in the inactivation gating structure of the sodium channel.
Skip Nav Destination
Article navigation
1 March 1978
Article|
March 01 1978
Removal of sodium channel inactivation in squid giant axons by n-bromoacetamide.
G S Oxford
C H Wu
T Narahashi
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1978) 71 (3): 227–247.
Citation
G S Oxford, C H Wu, T Narahashi; Removal of sodium channel inactivation in squid giant axons by n-bromoacetamide.. J Gen Physiol 1 March 1978; 71 (3): 227–247. doi: https://doi.org/10.1085/jgp.71.3.227
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
N-bromoacetamide removes a calcium-dependent component of channel opening from calcium-activated potassium channels in rat skeletal muscle.
J Gen Physiol (November,1985)
Effect of N-bromoacetamide on single sodium channel currents in excised membrane patches.
J Gen Physiol (March,1982)
Gating of Na channels. Inactivation modifiers discriminate among models.
J Gen Physiol (February,1987)
Email alerts
Advertisement