Avtor/Urednik     Križaj, I; Dolly, JO; Gubenšek, F
Naslov     Identification of the neuronal acceptor in bovine cortex for ammodytoxin C, a presynaptically neurotoxic phospholipase A2
Tip     članek
Vir     Biochemistry
Vol. in št.     Letnik 33, št. 46
Leto izdaje     1994
Obseg     str. 13938-45
Jezik     eng
Abstrakt     A specific, high-affinity binding site for ammodytoxin C in synaptic membranes from bovine cerebral cortex was detected and partially characterized. Equilibrium binding analysis revealed a single population of Š125IĆammodytoxin C acceptors with the following binding parameters: Kd = 6.0 nM and Bmax = 5.7 pmol/mg membrane protein. Such binding was strongly inhibited by three ammodytoxins (A, B, and C) and by crotoxin B. Vipera berus berus phospholipase A2 was a weaker inhibitor; nontoxic phospholipase A2, ammodytin I2, and the myotoxic phospholipase A2 homologue, ammodytin L, both from Vipera ammodytes ammodytes venom, inhibited binding only at very high concentrations, whereas alpha-dendrotoxin, beta-bungarotoxin, and crotoxin A had no influence on the Š125IĆammodytoxin C-specific binding. The ammodytoxin C neuronal binding site therefore overlaps, at least partially, with the neuronal acceptors for some of the related presynaptically neurotoxic phospholipases A2 (beta-neurotoxins). Š125IĆ-Ammodytoxin C was covalently attached to its acceptor by chemical cross-linking. Subsequent SDS-PAGE analysis followed by autoradiography revealed saturably labeled membrane components with apparent M(r) values of 51,000 (weaker band) and 53,000-56,000 (stronger band). Pretreatment of synaptic membranes with Staphylococcus aureus V-8 proteinase and proteinase K, heat, or low pH decreased the Š125IĆammodytoxin C-specific binding to various extents, but never abolished it completely. Membrane protein and certain phospholipids residing in its vicinity are therefore most likely involved in the binding of ammodytoxin C to bovine synaptic membranes.
Deskriptorji     CEREBRAL CORTEX
NEURONS
NEUROTOXINS
PHOSPHOLIPASES A
VIPER VENOMS
BINDING SITES
CATTLE
CEREBRAL CORTEX
DIMETHYL SUBERIMIDATE
SYNAPTIC MEMBRANES
VIPERIDAE