Required during meiosis for separation of sister chromatids and homologous chromosomes. Proteolytic cleavage of REC8 on chromosome arms by separin during anaphase I allows for homologous chromosome separation in meiosis I and cleavage of REC8 on centromeres during anaphase II allows for sister chromatid separation in meiosis II (By similarity). Interacts (phosphorylated and unphosphorylated form) with SMC3. Interacts with SYCP3. Interacts (phosphorylated and unphosphorylated form) with SMC1B. Does not interact with SMC1A. Interacts with RAD51 (By similarity). Forms a complex with EWSR1, PRDM9, SYCP3 and SYCP1; complex formation is dependent of phosphorylated form of REC8 and requires PRDM9 bound to hotspot DNA; EWSR1 joins PRDM9 with the chromosomal axis through REC8 (By similarity). In meiotic chromosomes, localized along axial elements in prophase from the leptotene to diplotene stages. At later prophase stages, diakinesis and metaphase I, localized along interstitial axes of chromosomes including both centromere and arm regions. No longer detected in arm regions in anaphase I but persists on centromere regions until metaphase II. Localized to centromeres and spindle poles in endopolyploid tumor cells. Expressed in testis and thymus. Expressed in the B-cell lines WI-L2-NS and Namalwa (at protein level). Phosphorylated. Belongs to the rad21 family.