Enables several functions, including DNA-binding transcription repressor activity, RNA polymerase II-specific; HLH domain binding activity; and RNA polymerase II cis-regulatory region sequence-specific DNA binding activity. Involved in several processes, including circulatory system development; regulation of gliogenesis; and regulation of transcription, DNA-templated. Acts upstream of or within several processes, including animal organ development; negative regulation of cell differentiation; and nervous system development. Located in cytoplasm and nucleus. Part of protein-containing complex. Is expressed in several structures, including alimentary system; branchial arch; central nervous system; foot bone; and sensory organ. Orthologous to human HES1 (hes family bHLH transcription factor 1). [provided by Alliance of Genome Resources, Apr 2022]