New insight into plant intramembrane proteases

The process of proteolysis is a factor involved in control of the proper development of the plant and its responses to a changeable environment. Recent research has shown that proteases are not only engaged in quality control and protein turnover processes but also participate in the process which is known as regulated membrane proteolysis (RIP). Four families of integral membrane proteases, belonging to three different classes, have been identified: serine intramembrane proteases known as rhomboid proteases, site-2 proteases belonging to zinc metalloproteases, and two families of aspartic proteases: presenilins and signal peptide peptidases. The studies concerning intramembrane proteases in higher plants are, however, focused on Arabidopsis thaliana. The aim of the study was to identify and retrieve protein sequences of intramembrane protease homologs from other higher plant species and perform a detailed analysis of their primary sequences as well as their phylogenetic relations. This approach allows us to indicate several previously undescribed issues which may provide important directions for further research.