Practice question

N-myristoylation is co-translational irreversible modification attaching 14-carbon saturated fatty acid myristate from myristoyl-CoA to target protein. N-myristoyltransferase NMT recognizes N-terminal sequence Met-Gly-X-X-X-Ser/Thr after methionine aminopeptidase removes initiator methionine, exposing glycine at position 2 for amide bond formation. The glycine requirement is absolute; replacement with other residues abolishes myristoylation. Myristate anchor provides weak membrane affinity that often cooperates with additional palmitoylation or polybasic cluster to stably tether proteins to inner leaflet of plasma membrane, Golgi and endomembranes. Src family kinases, MARCKS, recoverin and many viral proteins utilize myristoylation for membrane localization required for signal transduction, vesicular trafficking and assembly. Serine, cysteine and tyrosine are not acceptor sites for myristoylation; serine can be phosphorylated, cysteine palmitoylated or prenylated, and tyrosine sulfated or phosphorylated, highlighting glycine specificity that defines this lipid modification pathway in eukaryotes and some bacteria. Such detailed mechanistic insight is frequently examined in competitive tests including NEET, CUET, CSIR-NET and GATE where transporter classification, energetics and disease linkage are integrated into problem-solving questions.