The function of NECTIN1 (nectin cell adhesion molecule 1, Ensembl gene identifier ENSG00000110400) is as follows. Cell adhesion molecule that promotes cell-cell contacts and plays important roles in the development of the nervous system (PubMed:21325282). Acts by forming homophilic or heterophilic trans- dimers (PubMed:21325282). Heterophilic interactions have been detected between NECTIN1 and NECTIN3 and between NECTIN1 and NECTIN4 (By similarity). Involved in axon guidance by promoting contacts between the commissural axons and the floor plate cells (By similarity). Involved in synaptogegesis (By similarity). Has some neurite outgrowth- promoting activity (By similarity). Promotes formation of checkerboard- like cellular pattern of hair cells and supporting cells in the auditory epithelium via heterophilic interaction with NECTIN3: NECTIN1 is present in the membrane of hair cells and associates with NECTIN3 on supporting cells, thereby mediating heterotypic adhesion between these two cell types (By similarity). Required for enamel mineralization (By similarity). {ECO:0000250|UniProtKB:Q9JKF6, ECO:0000269|PubMed:21325282}. (Microbial infection) Acts as a receptor for herpes simplex virus 1/HHV-1, herpes simplex virus 2/HHV-2, and pseudorabies virus/PRV (PubMed:21980294, PubMed:25231300, PubMed:28381567, PubMed:28542478, PubMed:34587223, PubMed:38857290, PubMed:39048823, PubMed:39048830, PubMed:7721102, PubMed:9616127, PubMed:9657005). Constitutes the major receptor for herpes simplex virus 1/HHV-1 entry into host cells (PubMed:34587223). {ECO:0000269|PubMed:21980294, ECO:0000269|PubMed:25231300, ECO:0000269|PubMed:28381567, ECO:0000269|PubMed:28542478, ECO:0000269|PubMed:34587223, ECO:0000269|PubMed:38857290, ECO:0000269|PubMed:39048823, ECO:0000269|PubMed:39048830, ECO:0000269|PubMed:7721102, ECO:0000269|PubMed:9616127, ECO:0000269|PubMed:9657005}.