Izlaganje sa skupa

Heterogeneities m Acetylcholine Receptor from Torpedo Species

R. D. O'Brien ; Section of Neurobiology and Behavior, CorneH University, Ithaca, New York 14853, USA
R. E. Gibson ; Section of Neurobiology and Behavior, CorneH University, Ithaca, New York 14853, USA

Sažetak

Micro-heterogeneity of acetycholine receptor is described:
preparations differ in their proportions of low- and high-affinity
acetylcholine binding sites, with Kd for acetylcholine of 11 and
562 nM respectively. The low-affinity is absent from fresh membranes
or unpurified Triton X-100 exstracts, but fa the major
component of pure or oxidized preparations, and is therefore considered
an artifact. Positive cooperativity in all high-affinity preparations
is described, and used to explain how a Kd of 11 nM is
compatible with a physiological half-response at 1 μM. Oligomeric
variations in Torpedo species are described. T. caLifornica has two
major oligomers, H and L, and two minor ones, HH and LL. The
principal form is considered to be H; its molecular weight was
estimated by D20 experiments as 535 000. It is a dimer of L, and
a hexamer of LL. It is is proposed that HH is a nonspecific aggregate,
formed especially at low detergent concentrations.

Ključne riječi

Hrčak ID:

196625

URI

https://hrcak.srce.hr/196625

Datum izdavanja:

3.12.1975.

Posjeta: 638 *