Peroxin-22 is a integral peroxisomal membrane protein family. The N-terminus is in the matrix and the C-terminus is in the cytosol. The N-terminus carries a 25-amino acid peroxisome membrane-targeting signal. It interacts with the ubiquitin-conjugating peripheral peroxisomal membrane enzyme Pex4p anchoring it at the peroxisomal membrane. Both Pex proteins are involved at the same stage of peroxisome biogenesis [1]. Pex22p-Pex4p interaction is required for ubiquitination of peroxisomal import receptor Pex5p mediated by Pex4p [2-4].

1: Pex22p of Pichia pastoris, essential for peroxisomal matrix protein import, anchors the ubiquitin-conjugating enzyme, Pex4p, on the peroxisomal membrane. Koller A, Snyder WB, Faber KN, Wenzel TJ, Rangell L, Keller GA, Subramani S; J Cell Biol. 1999;146:99-112. PMID:10402463

2: A disulphide bond in the E2 enzyme Pex4p modulates ubiquitin-conjugating activity. Williams C, van den Berg M, Stanley WA, Wilmanns M, Distel B; Sci Rep. 2013;3:2212. PMID:23896733

3: Insights into ubiquitin-conjugating enzyme/ co-activator interactions from the structure of the Pex4p:Pex22p complex. Williams C, van den Berg M, Panjikar S, Stanley WA, Distel B, Wilmanns M; EMBO J. 2012;31:391-402. PMID:22085930

4: Structural insights into K48-linked ubiquitin chain formation by the Pex4p-Pex22p complex. Groves MR, Schroer CFE, Middleton AJ, Lunev S, Danda N, Ali AM, Marrink SJ, Williams C; Biochem Biophys Res Commun. 2018;496:562-567. PMID:29288668