dimerization/docking (D/D) domain found in nucleoside diphosphate kinase homolog 5 (NDKH5)-like family
The NDKH5 family includes NDKH5, Chlamydomonas reinhardtii flagellar radial spoke protein 23 (RSP23) and similar proteins. NDKH5, also called NME5, NDP kinase homolog 5, inhibitor of p53-induced apoptosis-beta (IPIA-beta), testis-specific nm23 homolog, or nm23-H5, is specifically expressed in testis germinal cells. It may not have NDK kinase activity. It confers protection from cell death by Bax and alters the cellular levels of several antioxidant enzymes including Gpx5. It may play a role in spermiogenesis by increasing the ability of late-stage spermatids to eliminate reactive oxygen species. RSP23, also called p61, is a functional Ca2+/calmodulin-regulated nucleoside diphosphate kinase (NDK) from the flagella of Chlamydomonas that is present in the radial spoke stalk. It binds calmodulin in a calcium-dependent manner. Members of this family contain a C-terminal domain that shows high sequence similarity to the dimerization/docking (D/D) domain of protein DPY-30/SDC1.
Jiyao W et al.(2023). "The conserved domain database in 2023.",