The presence of Nef accelerates endocytosis and lysosomal degradation of the transmembrane glycoprotein CD8. Nef facilitates a cascade of protein interactions that ultimately result in the degradation of internalized CD8 protein. The final set of protein interactions that direct Nef to the beta-subunit of the COPI coatomers are at this time unclear.
A number of sites within Nef are proposed to be required for CD8 down-regulation, the myristoylation signal and N-terminal anchor regions, the C-terminal flexible loop, and amino acid positions 57 to 58. Consistent with all reported Nef functions, the myristoylation signal was found to be essential for CD8 down-modulation. The flexible loop contains a dileucine-based internalization motif, which is flanked by acidic clusters and is involved in enhanced internalization of the Nef-CD4 complex.