Required to anchor acetylcholinesterase (ACHE) to the basal lamina of the neuromuscular junction and to the membrane of neuronal synapses in brain. Also able to organize ACHE into tetramers. Interacts with ACHE, probably through disulfide bonds. In the brain, PRIMA linked to ACHE is found in membrane rafts. Predominantly expressed in the central nervous system, including in the brain. Also expressed in muscle, heart and kidney. Isoform 1 may be predominant in the cortex and striatum, while isoform 2 is more abundant in the cerebellum. The proline-rich attachment domain (PRAD) binds the AChE catalytic subunits.