Protein Fatty Acid Acylation in Developing Cortical Neurons

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Abstract
Neuron‐enriched cultures derived from embryonic day 17 rat cerebral cortex were incubated in the presence of [3H]myristic or [3H]palmitic acid. Analysis of radiolabeled proteins by two‐dimensional gel electrophoresis and fluorography revealed extensive incorporation of fatty acids into a small number of neuronal proteins. The major acylated proteins had apparent molecular weights and isoelectric points as follows: 87,000, 4.3; 63,000, 4.4; 45,000, 4.4; and 20,000, 5.3. After labeling with [3H]myristic acid, the radioactivity associated with these proteins was identified as myristic acid, which was attached via an ester linkage. All four of the major acylated neuronal proteins were found to be membrane‐bound and enriched in growth cones. By virtue of its molecular weight, isoelectric point, subcellular distribution, and peptide map, the 87‐kilodalton polypeptide was shown to be equivalent to pp80, a phosphoprotein that has been described in developing and mature synaptic terminals. The 45‐kilo‐dalton acylated protein also appears to coincide with another growth cone phosphoprotein, pp40. Acylation may serve as a mechanism to regulate the function of these proteins, or may play a role in directing them to the nerve terminal membrane.