Plays a major role in controlling sexual phenotype (PubMed:18245372). Terminal global regulator in a well-characterized cascade of sex-determining genes (By similarity). Promotes female development (By similarity). Interacts with tra-2 to promote spermatogenesis (PubMed:11250902). Promotes spermatogenesis through the Tip60 HAT complex and by regulating the expression of genes, such as fog-3, required for male development (PubMed:24098152). Association with chromatin and at the fog-3 promoter requires wdr-5.1, and may also require wdr-5.2 (By similarity). With trr-1, activates the fog-3 gene to determine sperm/oocyte cell fate (PubMed:24098152). In hermaphrodites, binds to an intronic regulatory site in the ceh-30 gene, preventing ceh-30 transcription and thereby preventing survival of the CEM (cephalic male) sensory neurons (By similarity). Represses the expression of the transcription factor dmd-3 in hermaphrodites to govern the timing and extent of male tail tip morphogenesis (By similarity). Plays a role in controlling the sex-specific differentiation of PHC sensory neurons and represses the development of male-specific morphological features (By similarity). Interacts with the MX regulatory domain of tra-2. Localization with chromatin in the nucleus in part depends on normal function of wdr-5.1. Only isoform a is thought to bind DNA. Zinc fingers 3, 4 and 5 are the most important for DNA binding; removal of finger 5 almost abolishes DNA binding and prevents the selection of binding sites. Null mutants exhibit strong masculinization and male mating behavior. XX male mutants are infertile, produce sperm from day one of adulthood, but by day three of adulthood, switch from spermatogenesis to oogenesis and produce irregular oocytes. Mutants display early somatic gonad precursor lineage defects, whereby Z1 precursors divide with reverse polarity and Z4 precursors migrate prematurely. Most animals rectify these defects to produce normal male somatic gonad. RNAi-mediated knock-down in XO male animals yields a partially feminized germ line that contains both sperm and oocytes in males, but not hermaphrodites. Belongs to the GLI C2H2-type zinc-finger protein family.