Requirement for the β I and β IV tubulin isotypes in mammalian cilia

Nielsen et al., [2001: Curr Biol 11:529–533], based on studies in Drosophila , have proposed that β tubulin in axonemal microtubules must contain a specific acidic seven amino acid sequence in its carboxyl terminus. In mammals, the two β IV isotypes (β IVa and β IVb ) contain that sequence. In order to test the application of this hypothesis to mammals, we have examined the expression of β tubulin isotypes in four different ciliated tissues (trachea, ependyma, uterine tube, and testis) using isotype‐specific antibodies and indirect immunofluorescence. We find that β IV tubulin is present in all ciliated cell types examined, but so is β I tubulin. Taken together with recent studies that show that β I and β IV tubulin are both present in the cilia of vestibular hair cells, olfactory neurons, and nasal respiratory epithelial cells, we propose that both β I tubulin and β IV tubulin may be required for axonemal structures in mammals. Cell Motil. Cytoskeleton 55:213–220, 2003. © 2003 Wiley‐Liss, Inc.