Figure 1. MTMR4 is a PY-motif-containing protein expressed in muscle that interacts with Nedd4.

(A) Schematic diagram of human MTMR4, based on [33]. Protein domains predicted with SMART (http://smart.embl-heidelberg.de/) and PFSCAN (http://hits.isb-sib.ch/cgi-bin/PFSCAN) include GRAM (glucosyltransferase, Rab-like GTPase activator of myotubularins) domain, RID (Rac-induced recruitment domain), PTP/DSP domain, SID (SET-interacting domain), PY motif (XPPXY), CC (coiled-coil) domain and FYVE domain. (B) Western blot of hMTMR4, Nedd4 and tubulin from transfected (MTM tx) or untransfected (untx) HEK-293 lysate immunoprecipitated with anti-MTMR4 antibodies (MTM I.P.). Equal amounts of whole lysate were run as a control. (C) Lysates (lysate) and immunoprecipitates using anti-Nedd4 antibodies (Nedd4 I.P.) or anti-(p70 S6 kinase) antibodies (p70 S6 I.P.) as negative control, of HeLa cells transfected with HA–hMTMR4 wild-type (MTM WT), HA–hMTMR4 PY mutant (MTM PY), pcDNA 3.1 vector alone (vec) or untransfected (untx). Immunoblotting (IB) was performed with anti-HA (monoclonal) antibodies followed by anti-Nedd4 (polyclonal) antibodies and blots were stripped and re-probed with anti-tubulin antibodies as control. Molecular masses are indicated in kDa.