Transcription factor involved in epithelial development. Binds directly to the consensus DNA sequence 5'-AACCGGTT-3' (PubMed:18288204, PubMed:21081122). Important regulator of DSG1 in the context of hair anchorage and epidermal differentiation, participates in the maintenance of the skin barrier (PubMed:18288204, PubMed:24586629). There is no genetic interaction with GRHL3 no genetic interaction with GRHL3, no functional cooperativity due to diverse target gene selectivity during epithelia development (PubMed:21081122). Binds DNA as homodimer. Homodimer, also forms heterodimers with GRHL2 or GRHL3. Isoform 1 is highly expressed in brain, pancreas, tonsil, placenta and kidney. Isoform 2 is highly expressed in brain and liver. Expression in the skin is confined to the suprabasal layers of the epidermis and to the hair follicles. At 15.5 dpc isoform 1 is expressed predominantly in the skin and in the developing hair germ, isoform 2 is expressed predominantly in the epidermis. Mutants are healthy and fertile, but display an initial delay in coat growth, with older mice exhibiting hair loss as a result of poor anchoring or the hair shaft in the follicle. They show reduced numbers of abnormal desmosomes in the interfollicular epidermis. Develop palmoplantar keratoderma (PubMed:21081122). They also exhibit mild chronic skin barrier defects with altered keratinocyte terminal differentiation, increased expression of inflammatory markers and infiltration of the skin by immune cells. GRHL genes (GRHL1, GRHL2 and GRHL3) show a paradoxal 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.