Objective: To determine signals contained in the HIV-1 Gag precursor implicated in protein transport.
Design: To study the localization of truncated Gag proteins expressed in Saccharomyces cerevisiae.
Methods: Thin-section immunoelectron microscopy studies were performed on S. cerevisiae cells producing myristoylated or non-myristoylated Pr55gag, the core protein (p24) and several truncated Gag proteins.
Results: Pr55gag and the carboxy-terminal truncated Gag proteins were myristoylated and localized at the plasma membrane. p24 was localized in the nucleus or perinuclear membrane. However, addition of a myristoyl group to p24 targeted this molecule to the plasma membrane.
Conclusions: The myristoylated amino-terminal 214 amino acids are sufficient to target Pr55gag to the plasma membrane. Subcellular signals implicated in protein transport are present in the core p24 polypeptide which may become dominant or accessible in the absence of the amino-myristoyl group.