1.B.69 The Peroxysomal Membrane Porin 4 (PxMP4) Family

The PxMP4 Family consists of proteins in peroxysomes of poorly defined function called PxMP4 or PMP24.  However, they are homologous to mitochondrial inner membrane consituents of the Tim complex, Tim 17, Tim22 and Tim23 as well as chloroplast OEP16 proteins and a small subunit of the NADH:ubiquinone oxidoreductase complex; see small subunit in the fungal enzyme complex of 200 aas (P25710). The human PMP24 is silenced by DNA methylation in prostate cancer (Zhang et al. 2010). PxMP4 probably is a porin with an important transport function in peroxysomes (Visser et al. 2007). TMEM135 is thought to regulate the balance between mitochondrial fusion and fission and plays a role in regulating lipid droplet formation/tethering, fatty acid metabolism, and peroxisomal function. Beasley et al. 2021 highlighted the understanding of the various roles of TMEM135 in cellular processes, organelle function, calcium dynamics, and metabolism as of 2020. Genetic variants of TMEM135 and PEX5 in the peroxisomal pathway have been associated with cutaneous melanoma-specific survival (Wang et al. 2021).