The family includes CAX-interacting protein-1 (CXIP1)-like proteins which contain a GIY-YIG domain that shows statistically significant similarity to the N-terminal catalytic domains of GIY-YIG family of intron-encoded homing endonuclease I-TevI and catalytic GIY-YIG domain of nucleotide excision repair endonuclease UvrC. CAXIP1 is a novel PICOT (protein kinase C-interacting cousin of thioredoxin) domain-containing Arabidopsis protein that activates H+/Ca2+ exchanger CAX1, and its homolog CAX4, but not CAX2 or CAX3.