PISD
Function
Catalyzes the formation of phosphatidylethanolamine (PtdEtn) from phosphatidylserine (PtdSer) (PubMed:30488656, PubMed:30858161). Plays a central role in phospholipid metabolism and in the interorganelle trafficking of phosphatidylserine. May be involved in lipid droplet biogenesis at the endoplasmic reticulum membrane (By similarity).
Involvement in disease
Liberfarb syndrome
LIBF
An autosomal recessive multisystem disorder affecting the eye, ear, bone, and brain development. Clinical features include early-onset retinal degeneration, congenital cataracts, sensorineural hearing loss, microcephaly, intellectual disability, white matter changes, mild facial dysmorphism, and skeletal dysplasia with platyspondyly, scoliosis and short stature.
None
The disease is caused by variants affecting the gene represented in this entry.
Pathway
Phospholipid metabolism; phosphatidylethanolamine biosynthesis.
Post-translational modifications
Is synthesized initially as an inactive proenzyme. Formation of the active enzyme involves a self-maturation process in which the active site pyruvoyl group is generated from an internal serine residue via an autocatalytic post-translational modification. Two non-identical subunits are generated from the proenzyme in this reaction, and the pyruvate is formed at the N-terminus of the alpha chain, which is derived from the carboxyl end of the proenzyme. The autoendoproteolytic cleavage occurs by a canonical serine protease mechanism, in which the side chain hydroxyl group of the serine supplies its oxygen atom to form the C-terminus of the beta chain, while the remainder of the serine residue undergoes an oxidative deamination to produce ammonia and the pyruvoyl prosthetic group on the alpha chain. During this reaction, the Ser that is part of the protease active site of the proenzyme becomes the pyruvoyl prosthetic group, which constitutes an essential element of the active site of the mature decarboxylase.
Sequence Similarities
Belongs to the phosphatidylserine decarboxylase family. PSD-B subfamily. Eukaryotic type I sub-subfamily.
Cellular localization
- Phosphatidylserine decarboxylase beta chain
- Mitochondrion inner membrane
- Single-pass membrane protein
- Intermembrane side
- Phosphatidylserine decarboxylase alpha chain
- Mitochondrion inner membrane
- Peripheral membrane protein
- Intermembrane side
- Cytoplasm
- Anchored to the mitochondrial inner membrane through its interaction with the integral membrane beta chain.
- Isoform 1
- Mitochondrion inner membrane
- Isoform 2
- Mitochondrion inner membrane
- Lipid droplet
- Predominantly localizes to lipid droplets in lipid-replete conditions, and to mitochondria in lipid-deplete conditions.
Alternative names
PISD