Two classes of fatty acid acylated proteins exist in eukaryotic cells.

Labelling of cultured cells with [3H]palmitic and [3H]myristic acids demonstrates that each of these fatty acids modifies a substantially different subset of cellular proteins. Hydroxylamine treatment can be used to differentiate sensitive thioester linkages to palmitate from insensitive amide linkages to myristate. Several palmitoylated proteins are surface-oriented glycoproteins while all of the myristylated proteins appear to be internal. Myristate addition is much more tightly coupled to protein synthesis than palmitoylation, which is able to continue at a reduced level even in the prolonged absence of protein synthesis. Acyl proteins patterns were affected both qualitatively and quantitatively by transformation and growth status. The preferential addition of palmitate to the transferrin receptor and myristate to pp60src, and the absence of these modifications from several other proteins is reported. We propose a nomenclature for fatty acyl proteins based on these observations.