Is the acetylcholine releasing protein mediatophore present in rat brain?

Abstract

Mediatophore is a protein purified from the nerve terminal membranes ofTorpedo electric organ. It confers to artificial membranes a calcium‐dependent mechanism that translocates acetylcholine. When similar reconstitution experiments are applied to rat brain synaptosomal membranes they reveal the presence of mediatophore activity with properties close to those described for theTorpedo protein (extractability, sensitivity to calcium, and effect of the drug cetiedil). The acitivity was more abundant in synaptosomal membranes than in mitochondrial or myelinic membranes and in cholinergic areas as compared to cerebellum.

Synaptic Soluble and Membrane-Bound Choline Acetyltransferase as a Marker of Cholinergic Function In Vitro and In Vivo

“…The non-vesicular Ca 2+ -dependent pathway of the quantum secretion of ACh has been revealed [128][129][130][131]. It was shown that this pathway provides fast secretion of ACh by a synaptic membrane structural protein [132] called mediatophore [128].…”

Quantal neurotransmitter release: Vesicular or not vesicular?

“…The "mediatophore" protein, isolated from the membranes of Torpedo synaptosomes [85] and from the rat brain [57], and other so-called synaptic proteins may function as a part of the vesigate and play a role in the translocation of ACh. The vesigate hypothesis excludes vesicular exocytosis and simple ACh channels, but gives no indication of how the transmitter is translocated across the presynaptic-membrane.…”

Differential Targeting to the Plasma Membrane of the Torpedo 15‐kDa Proteolipid Expressed in Oocytes

“…Another origin of the 15-kDa proteolipid was the mediatophore complex purified from Torpedo electric organ synaptosomes (Birman et al, 1990) . The mediatophore is a presynaptic oligomeric protein of -150-200 kDa first purified from Torpedo electric organ synaptosomes and later from the brain and the neural region of skeletal muscles of the rat (Israël et al, 1988 . Incorporated into artificial lipid bilayers, this protein is able to translocate acetylcholine (ACh) in response to a calcium influx (Israël et al, 1986) and shares several other properties of transmitter release observed in situ (Israël et al, 1984(Israël et al, , 1986(Israël et al, , 1987 .…”