Anti-HYDIN axonemal central pair apparatus protein antibodies are used for the immunodetection of the protein encoded by the HYDIN gene. In humans, the canonical protein has a reported length of 5121 amino acid residues and a mass of 575.9 kDa. Its subcellular localization is in the cell projections and cytoplasm. Alternative splicing is reported to yield 6 different isoforms for this protein. It is known to be required for ciliary motility. The gene encoding this protein is implicated in Ciliary dyskinesia. Other names for this target antigen include HYDIN1, HYDIN2, PPP1R31, hydrocephalus-inducing protein homolog, protein phosphatase 1, regulatory subunit 31, and CILD5. Gene orthologs have been identified in the mouse, rat, frog, zebrafish, chimpanzee and chicken species.