Plays a role in cellular signaling via Rho-related GTP-binding proteins and subsequent activation of transcription factor SRF (By similarity). Targets TJP1 to cell junctions. In cortical neurons, may play a role in glutaminergic signal transduction through interaction with the NMDA receptor subunit GRIN1 (By similarity). Interacts with DSP, MPRIP and TJP1/ZO1. Interaction with MPRIP inhibits the activation of transcription factor SRF (By similarity). Interacts with GRIN1. Interacts with DYNLL1. Detected predominantly at the intercalated disk in cardiomyocytes, and at low levels on sarcomeric Z disks. Colocalizes with F-actin. Colocalizes with cortical actin. Additional isoforms seem to exist. Detected in heart, liver, skeletal muscle, placenta, small intestine, lung, prostate and testis. Expressed in arrector pili muscle (at protein level) (PubMed:29034528). The adjacent MYZAP and POLR2M genes are part of a complex transcription unit. The respective transcripts derive from different promoters and are alternatively spliced. In human, some transcripts of the upstream promoter of MYZAP use exons of the downstream POLR2M gene. Based on a naturally occurring readthrough transcript which produces a MYZAP-POLR2M fusion protein. Belongs to the MYZAP family.