Subcellular distribution of glutamyltransferase activities in embryonic cerebral hemispheres.

Glutamyltransferase (GT) activities were examined in cell groups from embryonic cerebral hemispheres. During normal development, GT activities were highest in a mixed population of small neurons and non-neuronal cells (small cell group). In culture, in response to hydrocortisone, activities exceeded normal levels only in this small cell group. In view of these findings, the small cell population was used to study the subcellular distribution of the enzyme. At the subcellular level, GT activities in the small cell group were distributed differentially but increased generally during normal development. In vitro, hydrocortisone promoted a precocious increase in GT activity, under experimental conditions regarded as optimum, only in the subcellular fraction characterized by synaptic endings.