Intraneuronal alpha-fetoprotein and albumin are not synthesized locally in developing brain.

Alpha-Fetoprotein and albumin are found intraneuronally in developing mammalian brains. To investigate whether this results from local biosynthesis, the existence of the corresponding brain messenger RNAs and the ability of brain cultures to synthesize these proteins were studied in the mouse. The findings show that neither the proteins nor the mRNAs coding for them are made in sufficient quantities to account for the material detected immunologically, supporting an extracellular origin.