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).


This family belongs to the Outer Membrane Pore-forming Protein IV (OMPP-IV) Superfamily .
 

References:

Beasley, H.K., T.A. Rodman, G.V. Collins, A. Hinton, Jr, and V. Exil. (2021). TMEM135 is a Novel Regulator of Mitochondrial Dynamics and Physiology with Implications for Human Health Conditions. Cells 10:.
Beck, R., F. Adolf, C. Weimer, B. Bruegger, and F.T. Wieland. (2009). ArfGAP1 activity and COPI vesicle biogenesis. Traffic 10: 307-315.
Visser, W.F., C.W. van Roermund, L. Ijlst, H.R. Waterham, and R.J. Wanders. (2007). Metabolite transport across the peroxisomal membrane. Biochem. J. 401: 365-375.
Wang, H., H. Liu, W. Dai, S. Luo, C.I. Amos, J.E. Lee, X. Li, Y. Yue, H. Nan, and Q. Wei. (2021). Association of genetic variants of and in the peroxisome pathway with cutaneous melanoma-specific survival. Ann Transl Med 9: 396.
Zhang, X., M. Wu, H. Xiao, M.T. Lee, L. Levin, Y.K. Leung, and S.M. Ho. (2010). Methylation of a single intronic CpG mediates expression silencing of the PMP24 gene in prostate cancer. Prostate 70: 765-776.
Examples:

TC#NameOrganismal TypeExample
1.B.69.1.1

PxMP4 or MPM24 of 212 aas and 4 TMSs.

Animals

PxMP4 of Homo sapiens

 
1.B.69.1.2

PMP24 of 226 aas and 4 TMSs.

Protozoans

PMP24 of Leishmania mexicana

 
1.B.69.1.3

PMP24 of 216 aas.

Amoeba

PMP24 of Acanthamoeba castellanii

 
1.B.69.1.4

PMP24 of 217 aas.

Fungi

PMP24 of Aspergillus niger

 
1.B.69.1.5

Uncharacterized protein of 230 aas and 3 TMSs

Amoebozoa

UP of Polysphondylium pallidum (Cellular slime mold)

 
1.B.69.1.6

Uncharacterized protein of 211 TMSs

Fungi

UP of Laccaria bicolor

 
1.B.69.1.7

Uncharacterized protein of 202 aas and 4 TMSs

Alveolata (ciliates)

UP of Paramecium tetraurelia

 
1.B.69.1.8

Uncharacterized protein of 248 aas and 3 TMSs

Fungi

UP of Ustilago maydis

 
Examples:

TC#NameOrganismal TypeExample
1.B.69.2.1

Putative internally duplicated porin of 555 aas with each half probably having 4 TMSs.

Plants

Sorghum bicolor (Sorghum) (Sorghum vulgare)

 
1.B.69.2.2

Uncharacterized protein of 559 aas

Plants

UP of Brachypodium distachyon (Purple false brome) (Trachynia distachya)

 
1.B.69.2.3

Internally duplicated putative porin of 513 aas and 8 - 10 TMSs.

Fungi

UP of Cladophialophora psammophila

 
1.B.69.2.4

Uncharacterized protein of 513 aas and ~8 TMSs.

Euglenozoa

UP of Leishmania donovani

 
1.B.69.2.5

Uncharacterized protein of 453 aas and 9 TMSs.

Animals

UP of Xenopus laevis (African clawed frog)