Vesicle Structural Changes Control Content Release of Transmitters and Hormones

Shape bistability of a membrane neck: a toggle switch to control vesicle content release.

Shape dynamics and permeability of a membrane neck connecting a vesicle and plasma membrane are considered. The neck is modeled by a lipid membrane tubule extended between two parallel axisymmetric rings. Within a range of lengths, defined by system geometry and mechanical properties of the membrane, the tubule has two stable shapes: catenoidal microtubule and cylindrical nanotubule. The permea...

Content-based protection and release access control

Aplysia synaptosomes. II. Release of transmitters.

A subcellular fraction (P3) from Aplysia is enriched in synaptosomes (Chin et al., 1988) and is capable of accumulating 5-HT and choline. At an external 3H-5-HT concentration of 1.8 microM, the P3 fraction took up 0.12 nmol/mg protein in 30 min. Uptake was dependent on external Na+. Electron microscopic autoradiography showed that much of the accumulated 3H-5-HT is localized to synaptosomes. At...

Effects of anaesthetics on uptake, synthesis and release of transmitters.

While the molecular basis of the action of most anaesthetic agents is unknown, it is a commonly held view that general anaesthetic drugs have a more pronounced effect on synaptic mechanisms in the central nervous system (CNS) than on the propagation of electrical signals along axons [39]. A more contentious issue relates to whether or not anaesthetic agents act generally, producing a range of m...

Structural changes of bacteriophage phi29 upon DNA packaging and release.

Cryo-electron microscopy three-dimensional reconstructions have been made of mature and of emptied bacteriophage phi29 particles without making symmetry assumptions. Comparisons of these structures with each other and with the phi29 prohead indicate how conformational changes might initiate successive steps of assembly and infection. The 12 adsorption capable 'appendages' were found to have a s...