Radial Spoke Head 4 Homolog A (RSPH4A)

RSPH4A encodes a protein that appears to be a component the radial spoke head, as determined by homology to similar proteins in the biflagellate alga Chlamydomonas reinhardtii and other ciliates. Radial spokes, which are regularly spaced along cilia, sperm, and flagella axonemes, consist of a thin 'stalk' and a bulbous 'head' that form a signal transduction scaffold between the central pair of microtubules and dynein.

Mutations in this gene cause primary ciliary dyskinesia 1, a disease arising from dysmotility of motile cilia and sperm. Alternative splicing results in multiple transcript variants. The deduced RSPH4A protein contains 716 amino acids and shares about 30% identity with the Chlamydomonas radial spoke head proteins Rsp4 and Rsp6.