dimerization/docking (D/D) domain found in Chlamydomonas reinhardtii flagellar radial spoke protein 23 (RSP23) and similar proteins
Flagellar radial spokes contribute to the regulation of dynein arm activity and thus the pattern of flagellar bending. They consist of a thin stalk, which is attached to the a subfiber of the outer doublet microtubule, and a bulbous head, which is attached to the stalk and appears to interact with the projections from the central pair of microtubules. RSP23, also called p61, is a functional Ca2+/calmodulin-regulated nucleoside diphosphate kinase (NDK) from flagella of Chlamydomonas that is present in the radial spoke stalk. It binds calmodulin in a calcium-dependent manner. RSP23 consists of an N-terminal catalytic NDK domain followed by a repetitive region that includes three IQ motifs and a highly acidic C-terminal segment, which 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.",