Central component of the condensin I-like dosage compensation complex that associates specifically with hermaphrodite X chromosomes to reduce their gene transcription throughout development (PubMed:7954812, PubMed:3779843, PubMed:26641248, PubMed:8939870, PubMed:14660541, PubMed:22393255, PubMed:19119011). Its strong similarity with the condensin subunit smc4 suggests that it may reduce the X-chromosome transcript level by condensing the chromatin structure during interphase (PubMed:8939870). Involved in the recruitment of the dosage compensation proteins mix-1 and dpy-21 to the X chromosome (PubMed:14660541, PubMed:9458050). Might be involved in the reduction of histone H4 lysine 16 acetylation (H4K16ac) on dosage compensated X chromosomes (PubMed:22393255). As a member of the dosage compensation complex, also binds to regulatory regions of the autosomal her-1 gene, required for male development, possibly contributing to its repression in hermaphrodites (PubMed:11937488). Also plays a role in the regulation of growth and body fat metabolism downstream of the TOR complex 2 pathway (PubMed:23884442). Component of the dosage compensation complex, which contains the mix-1/SMC2 and dpy-27/SMC4 heterodimer, and three non SMC subunits that probably regulate the complex: dpy-26, capg-1 and dpy-28 (PubMed:8939870, PubMed:15557118, PubMed:18198337, PubMed:19781752, PubMed:19119011). Within the complex, interacts with dpy-28, mix-1, dpy-26 and capg-1 (PubMed:15557118, PubMed:18198337, PubMed:19781752, PubMed:19119011, PubMed:9458050, PubMed:28301465). Interacts with dpy-21 (PubMed:14660541). Interacts with dpy-28; the interaction is required for dpy-28 protein stability and dpy-28 association with the X chromosome (PubMed:18198337). Interacts with smcl-1 (PubMed:28301465). In interphase cells, diffusely distributed in nuclei before the onset of dosage compensation (PubMed:19119011). Associates with chromatin after the 30-cell stage when dosage compensation is initiated (PubMed:7954812, PubMed:23028348, PubMed:19119011). Specifically localizes to the X chromosomes of hermaphrodite (XX) embryos, but remains diffusely distributed throughout the nuclei of male (XO) embryos (PubMed:7954812, PubMed:23028348). dpy-26 is required for its X chromosome specific association (PubMed:8939870). Expressed in embryos and early-staged larvae (PubMed:7954812). Also expressed in adult gut nuclei (PubMed:14660541). Consists of two putative central coiled-coil regions flanked by putative globular regions at the N- and C-termini. RNAi-mediated knockdown causes derepression of X chromosome linked genes in embryos and in larval stages L1 and L3 (PubMed:26641248). Leads to an increase of 'Lys-16' acetylation of histone H4 (H4K16ac) on hermaphrodite X chromosomes (PubMed:22393255). In the TOR complex 2 mutant background rict-1, suppresses the growth delay and elevated body fat index (PubMed:23884442). In a sex-1 mutant background, leads to high XX-specific embryonic lethality (PubMed:19119011). Belongs to the SMC family. SMC4 subfamily.