Phylogenetic analysis of plant calreticulin homologs.

Calreticulin (CRT) is an multifunctional resident endoplasmic reticulum (ER) luminal protein implicated in regulating a variety of cellular processes, including Ca storage/mobilization and protein folding. These multiple functions may be carried out by different CRT genes and protein isoforms. The plant CRT family consist of three genes: CRT1 and CRT2 classified in the common subclass (CRT1/2), and CRT3. These genes are highly conserved during evolution and encode three different protein products (CRT1, 2 and 3). The aim of the current study was to conduct a comparative analysis and sequence-based classification of the plant CRT genes. We used nucleotide and amino acid sequences to phylogenetically cluster the genes and examine potential glycosylation patterns. Additionally, we analyzed phylogenetic relationships within the CRT subclasses. Finally, we analyzed intraspecific CRT duplication events among mono- and dicotyledon species. Our results confirm that each of the CRT genes exist in multiple copies in plant genomes, and that CRT gene duplication is a widespread process in plants.