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Further characterization of brain actin by electron microscopy.
Journal of Neuropathology and Experimental Neurology
|March 1, 1977
Summary
Actin in nerve endings is not fully polymerized but associates with synaptic membranes. Muscle heaving meromyosin (HMM) can induce actin polymerization, forming characteristic arrowhead-decorated fibers.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Actin dynamics are crucial for neuronal function.
- The precise state and localization of actin in nerve endings remain incompletely understood.
Purpose of the Study:
- To investigate the physical state of actin in nerve ending preparations.
- To determine the relationship between actin and synaptic membranes at the ultrastructural level.
Main Methods:
- Negative staining with uranyl acetate for ultrastructural analysis.
- Treatment with muscle heaving meromyosin (HMM) to assess actin polymerization.
Main Results:
- Brain actin polymerized less readily than muscle actin.
- HMM treatment induced arrowhead-decorated fiber formation in synaptosomal and synaptic membrane fractions.
- Presynaptic vesicle fractions did not show HMM-induced fiber formation.
Conclusions:
- Actin in nerve endings is partially or non-polymerized and associated with synaptic membranes.
- Heaving meromyosin (HMM) can induce actin polymerization in these preparations.