May play a role in plant defense signaling (Probable). Isoform 2 binds to phospholipids in a Ca(2+)-dependent manner in response to pathogen elicitors (PubMed:14529272). Binds 3 Ca(2+) ions per C2 domain. Translocates to plasma membrane upon fungal elicitor or calcium treatment. Isoform 2 is expressed in young vascular tissues and tiller buds. By fungal elicitor and calcium. Phosphorylated at Ser-44 by CPK18 in a calcium-dependent manner.