ABSTRACT

Myristoyl CoA: protein N-myristoyltransferase (NMT) is the enzyme that catalyzes the covalent transfer of myristic acid (a 14-carbon fatty acid) to the N-terminal glycine residue of a protein substrate. In addition, either serine or threonine at fifth position from N-terminal glycine is preferred residue for myristoylation. Originally, our laboratory has provided the evidence for the existence of multiple forms of NMT in bovine brain. In addition, we have discovered NMT inhibitor protein (NIP₇₁), which is located in the particulate fraction of bovine brain. NIP₇₁ was stable to heat and had an apparent molecular mass of 71 kDa under denaturing conditions. NIP₇₁ did not interact with myristoyl-CoA and possessed no protease, thioesterase or demyristoylase activity. Furthermore, during purification of NMT form bovine brain, we identified an NMT activating factor (NAF₄₅). The studies suggested that NAF₄₅ was able to compete with NIP₇₁. At present, the physiological role of NIP₇₁ and NAF₄₅ are under investigation in our laboratory.