GINKGO-BILOBA EXPRESSES CALRETICULIN, THE MAJOR CALCIUM-BINDING RETICULOPLASMIN IN EUKARYOTIC CELLS

Calreticulin, the main Ca2+ binding protein in the endoplasmic reticul um of eukaryotic cells, was characterized in Ginkgo biloba L. pollen a nd seeds. Electrophoretic analysis of the partly purified extracts sho wed the presence of two protein bands of 57 and 50 kDa apparent molecu lar masses, which strongly cross-reacted with antibodies against plant calreticulins. Amino acid sequence comparison with other plant and an imal calreticulins revealed a much higher similarity of the N-terminus of Ginkgo calreticulins with the homologue from angiosperms rather th an with that from mammals. The finding of calreticulin in Ginkgo is in dicative of the conservation also in gymnosperms of Ca2+ homeostatic m echanisms, which seem to rely on the same molecular components as all eukaryotic cells.