Molecular forms of acetylcholinesterase: their de novo synthesis in mouse neuroblastoma cells.

Rat mouse AChE molecular forms are indistinguishable with respect to their sedimentation coefficients and their evolutive proportions during brain maturation. Among rat or mouse erythrocytes, rat C6 glial cells, and mouse 2A and NS 20 neuroblastoma cells, only neuroblastoma cells showed both the ES and HS molecular forms with a 1:1 proportion for NS 20 cells. All these cells lack a third molecular form (16S), which is present in rat and mouse superior cervical ganglia. After irreversible inhibition of pre-existing NS 20 neuroblastoma AchE, the ES form is first synthesized (de novo synthesis). The HS form begins to appear after a lag time of several hours and represents, 24 h after inhibition, only 15% of the total recovered activity, which is near the initial level. The initial relative proportions return by 2 to 3 days after inhibition. The recovery of the HS form is, for the most part, blocked by actinomycin D, which does not block the recovery of activity itself, which remains as an ES form. It seems that integration of the ES form into the HS form more probably depends on the synthesis of a new messenger RNA, which is required for the synthesis of either new AChE polypeptide chain, polymerization initiating protein or activating enzyme.