The C-terminal region of the E3 ubiquitin ligase MKRN1 interacts with PTEN and polyubiquitinates it on lysine residue K289, via K48 linkage. AKT-mediated phosphorylation of MKRN1 on serine residue S109 is a pre-requisite for MKRN1 stabilization and MKRN1-mediated ubiquitination of PTEN. MKRN1 is implicated as an oncogene in cervical cancer (Lee et al. 2015).
ubiquitin protein ligase activity of p-S109-MKRN1 [cytosol]