Sequence analysis of keratin-like proteins and cloning of intermediate filament-like cDNA from higher plant cells

Two keratin-like proteins of 64 and 55 ku were purified from suspension cells ofDaucus carota L., and their partial amino acid sequences were determined. The homological analysis showed that the sequence from the 64 ku protein was highly homological to β-glucosidase, and that from the 55 ku protein had no significant homologue in GenBank. Using conservative sequence of animal IF proteins as primer, we cloned a cDNA fragment fromDaucus carota L. Southern blot and Northern blot results indicated that this cDNA fragment was a single copy gene and expressed both in suspension cells and leaves. Homological analysis revealed that it had moderate homology to a variety of α-helical proteins. Our results might shed more light on molecular characterization of IF existence in higher plant.