A component of desmosome cell-cell junctions which are required for positive regulation of cellular adhesion (PubMed:19717567). Promotes differentiation of keratinocytes via interaction with ERBIN. Reduces activation of RAS/ERK signaling pathways in keratinocytes via promoting ERBIN localization to the cell membrane and its interaction with SHOC2, this competitively reduces the formation of RAS-SHOC2 ERK-activating complexes (PubMed:23524970). Mediates the interaction between the desmosome and COP9 signalosome complex (CSN) protein complex (PubMed:28891468). As a result of this interaction, promotes keratinocyte differentiation via deneddylation of EGFR resulting in a reduction in EGFR protein stabilization and translocation away from the cell membrane (PubMed:28891468). Critical for epidermal integrity and barrier function of the skin (By similarity). Required for esophageal epithelial barrier integrity and correct intercellular spacing in differentiated esophageal epithelium (PubMed:24220297). Required for recovery of epidermal architecture and correct expression of differentiation markers following UVB exposure (PubMed:24594668). May also be required for OCLN involvement in tight junctions (By similarity). {ECO:0000250|UniProtKB:Q61495, ECO:0000269|PubMed:19717567, ECO:0000269|PubMed:23524970, ECO:0000269|PubMed:24220297, ECO:0000269|PubMed:24594668, ECO:0000269|PubMed:28891468, ECO:0000269|PubMed:34368962}. This is the function of DSG1 (desmoglein 1, ENSG00000134760).