TMED9
Description
The TMED9 (transmembrane p24 trafficking protein 9) is a protein-coding gene located on chromosome 5.
The p24 protein family is a group of transmembrane proteins that are key components of COPI and COPII-coated vesicles, also known as EMP24/GP25L/p24 family and TMP21-like proteins. This family is named after transmembrane emp24 domain-containing protein 10, discovered in the human brain, which was purported to block the beta-amyloid peptide, a factor implicated in Alzheimer's disease. These proteins are localized to the major organelles of the early secretory pathway: the endoplasmic reticulum and the Golgi apparatus, where they play a role in trafficking between the two compartments. Although all p24 family proteins can be removed in yeast with only a mild phenotype, in mammals some are essential for survival, as demonstrated by the lethality in mice after removal of p24Ξ΄1. The p24 family members have been linked to the biogenesis of COPI and COPII-coated vesicles, transporting membrane-bound proteins through the secretory system, and forming the structure of the endoplasmic reticulum and Golgi. Most p24 family proteins exhibit widespread expression in various tissues.
TMED9 appears to play a role in vesicular protein trafficking, particularly in the early secretory pathway. It participates in COPI vesicle-mediated retrograde transport by facilitating the recruitment of coatomer to membranes within this pathway. TMED9 enhances the coatomer-dependent activity of ARFGAP2. It is believed to have a crucial role in retaining p24 complexes specifically within cis-Golgi membranes and contributes to the co-localization of TMED2 and TMED10 in the cis-Golgi network. TMED9 may also be involved in organizing intracellular membranes, including the ER-Golgi intermediate compartment and the Golgi apparatus. It plays a role in the ER localization of PTPN2 isoform PTPB.
TMED9 is also known as GMP25, HSGP25L2G, p24a2, p24alpha2, p25.
