Required for polar body extrusion during cytokinesis in embryo development. Affects cortical granule size. Has roles in meiotic chromosome segregation, osmotic barrier function and polarization in conjunction with cpg-2. Binds chitin. Expressed in the germline. Expressed throughout development but appears to be up-regulated in adults. Worms lacking cpg-2 and cpg-1 exhibit defects in cytokinesis during embryo development more specifically meiotic chromosome segregation, polar-body extrusion, osmotic barrier function and polarization. Embryos lacking cpg-2 and cpg-1 proteins have multiple nuclei lacking plasma membranes and may also have weak egg shells. Oocytes lacking cpg-2 and cpg-1 show cortical granules that are reduced in size.