Beta-tubulins are encoded by at least four genes in the brown alga Ectocarpus variabilis.

Complementary DNA clones of two mRNA species that encode beta-tubulin in the brown alga Ectocarpus variabilis have been isolated. Sequence analysis revealed that the encoded proteins are very similar in primary structure to homologues in other eukaryotes, and differ from each other at six of 447 amino acid residues. The beta 6 message shows a preference for C- or G-terminated codons, using only 49 codons. The beta 5 message has a lesser codon bias, and makes a minor contribution to the beta-tubulin mRNA pool. Southern analysis of E. variabilis DNA demonstrated a beta-tubulin gene family of at least four members.