Vectorial Discharge and Localization of Nascent Polypeptides in Rough Endoplasmic Reticulum of Developing Neuronal Perikarya of Rat Brain Cortex

Abstract

Rough endoplasmic reticulum (RER) prepared from bulk-isolated neuronal perikarya of rat brain cortex of different postnatal ages was found to be active in vectorial discharge of nascent proteins through the membrane; this activity increased with the increasing age of animals and reached maximal values in adults. RER isolated from whole cortical tissue (containing all cell types) exhibited vectorial release only up to 18 days of age; the preparation from adult animals was essentially devoid of secretory activity. Controlled proteolysis of various preparations suggested that in neuronal RER of 8-day-old rats the proportion of nascent proteins operationally retained in the intravesicular space was about twice that retained by cortical preparations. For the purpose of comparison, these parameters were studied also in liver RER.

Decreased Transcription of Neuronal Polyadenylated RNA During Senescence in Nuclei from Rat Brain Cortex

“…The incubation was done at 35°C for 60 min, and the trichloroacetic acid-insoluble radioactivity was determined. DNA, RNA, ' : 1 1 6 12 18 B Age (months) and radioactivity were determined as described previously (Khawaja and Lindholm, 1984).…”