E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of myosin regulatory light chain (MRLC), LDLR, VLDLR and LRP8. Activity depends on E2 enzymes of the UBE2D family. Proteasomal degradation of MRLC leads to inhibit neurite outgrowth in presence of NGF by counteracting the stabilization of MRLC by saposin-like protein (CNPY2/MSAP) and reducing CNPY2-stimulated neurite outgrowth. Acts as a sterol-dependent inhibitor of cellular cholesterol uptake by mediating ubiquitination and subsequent degradation of LDLR. {ECO:0000269|PubMed:10593918, ECO:0000269|PubMed:12826659, ECO:0000269|PubMed:14550572, ECO:0000269|PubMed:19520913, ECO:0000269|PubMed:20427281, ECO:0000269|PubMed:22109552}. This is the function of MYLIP (myosin regulatory light chain interacting protein, ENSG00000007944).