The low affinity neurotrophin receptor, p75LNTR, is palmitoylated by thioester formation through cysteine 279

Abstract

The low affinity neurotrophin receptor, termed p75LNTR, plays a role in increasing the amount of nerve growth factor that becomes bound to the tyrosine kinase receptor, trkA (Barker, P. A., and Shooter, E. M. (1994) Neuron 13: 203-215), possibly by increasing the nerve growth factor concentration in the microenvironment surrounding the trkA receptor. Because protein acylation may be a means by which cell surface receptor distribution may be regulated, we have determined the acylation status of p75LNTR. We find that p75LNTR expressed in PC12, PCNA, or transfected COS cells is metabolically labeled with [3H]palmitic acid. This modification occurs post-translationally, and the incorporated fatty acid is removed by hydroxylamine treatment at pH 7 or 11 and by sulfhydryl reducing agents, suggesting a thioester linkage to palmitic acid. Consistent with this, p75LNTR in which the juxtamembrane cysteine present at position 279 is substituted with alanine is expressed but cannot be metabolically labeled with [3H]palmitic acid. Substitution of other cysteine residues present in the transmembrane or intracellular domain of the receptor has no effect on protein acylation, suggesting that only Cys279 is esterified to palmitate.