There are two repeated peptides, [S,T,Y]QQ[Y,M] and MFR[R,X][V,K], which appear three times each in the region corresponding to the third exon of carrot beta-tubulins. The former peptide is flanked on both sides by a pair of identically charged groups and the latter includes two or three basic amino acids in it. The sequences are generally conserved well among the eukaryotes except for fungi, in which one of the peptides, SQQY, does not exist.