This gene encodes a protein with an N-terminal thioredoxin domain and three C-terminal nucleoside diphosphate kinase (NDK) domains, but the NDK domains are thought to be catalytically inactive. The sea urchin ortholog of this gene encodes a component of sperm outer dynein arms, and the protein is implicated in ciliary function. Mutations in this gene are implicated in primary ciliary dyskinesia type 6.