Transcription factor playing important roles in primary neurulation and in the differentiation of stratified epithelia of both ectodermal and endodermal origin (By similarity). Binds directly to the consensus DNA sequence 5'-AACCGGTT-3' acting as an activator and repressor on distinct target genes (PubMed:21081122, PubMed:25347468). xhibits functional redundancy with GRHL2 in epidermal morphogenetic events and epidermal wound repair (By similarity). Exhibits functional redundancy with GRHL2 in epidermal morphogenetic events and epidermal wound repair but is essential to form the epidermal barrier with TGM3 as critical direct target gene among others. Despite being dispensable during normal epidermal homeostasis in the adulthood, is again required for barrier repair after immune-mediated epidermal damage, regulates distinct gene batteries in embryonic epidermal differentiation and adult epidermal barrier reformation after injury. Plays unique and cooperative roles with GRHL2 in establishing distinct zones of primary neurulation. Essential for spinal closure, functions cooperatively with GRHL2 in closure 2 (forebrain/midbrain boundary) and posterior neuropore closure (By similarity). Also required for proper development of the oral periderm (PubMed:24360809). No genetic interaction with GRHL3, no functional cooperativity due to diverse target gene selectivity (PubMed:21081122). Homodimer, also forms heterodimers with GRHL1 and GRHL2 (PubMed:12549979). Interacts with LMO4 (By similarity). Expressed in brain, colon, pancreas, placenta and kidney. Isoform 1 is expressed in lung and tonsil. Isoform 2 is prostate-specific. The disease is caused by variants affecting the gene represented in this entry. GRHL genes (GRHL1, GRHL2 and GRHL3) show a paradoxical lack of redundancy despite their extensive sequence identity in the DNA-binding and protein dimerization domains and the fact that the core consensus DNA binding sites are identical. They have related, but remarkably different functions during embryogenesis because of their differential spatiotemporal expression patterns during development. Belongs to the grh/CP2 family. Grainyhead subfamily. Truncated N-terminus. Truncated N-terminus.