Peptidase M48 subfamily A, a type 1 CaaX endopeptidase
This family contains peptidase family M48 subfamily A which includes a number of well-characterized genes such as those found in humans (ZMPSTE24, also known as farnesylated protein-converting enzyme 1 or FACE-1 or Hs Ste24), Taenia solium metacestode (TsSte24p), Arabidopsis (AtSte24) and yeast (Ste24p). Ste24p contains the zinc metalloprotease motif (HEXXH), likely exposed on the cytoplasmic side. It is thought to be intimately associated with the endoplasmic reticulum (ER), regardless of whether its genes possess the conventional signal motif (KKXX) in the C-terminal. Proteins in this family proteolytically remove the C-terminal three residues of farnesylated proteins. Ste24p is involved in the post-translational processing of prelamin A to mature lamin A, a major component of the nuclear envelope. ZmpSte24 deficiency causes an accumulation of prelamin A leading to lipodystrophy and other disease phenotypes, while mutations in this gene or in that encoding its substrate, prelamin A, result in a series of human inherited diseases known as laminopathies, the most severe of which are Hutchinson Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) which arise due to unsuccessful maturation of prelamin A. Two forms of mandibuloacral dysplasia, a condition that causes a variety of abnormalities involving bone development, skin pigmentation, and fat distribution, are caused by mutations in two different genes; mutations in the LMNA gene, which normally provides instructions for making lamin A and lamin C, cause mandibuloacral dysplasia with A-type lipodystrophy (MAD-A), and mutations in the ZMPSTE24 gene cause mandibuloacral dysplasia with B-type lipodystrophy (MAD-B). Within cells, these genes are involved in maintaining the structure of the nucleus and may play a role in many cellular processes. Certain HIV protease inhibitors have been shown to inhibit the enzymatic activity of ZMPSTE24, but not enzymes involved in prelamin A processing.