The ancient roots of calcium signalling evolutionary tree

- Fundamental elements of cellular Ca2+ homeostasis are conserved from bacteria to human.
- These include Ca2+-pumps and exchangers, Ca2+ influx channels as well as some CaBPs, such as calmodulin, which all are present in prokaryotes.
- The Ca2+/calmodulin-activated protein phosphatase PP2B (calcineurin) is engaged in manifold signalling from different protozoa up to human.
- However, there is a discrepancy between overt InsP3 effects observed and the failure to identify InsP3R-type genomic sequences in some organisms. The recent focus on choanoflagellates as ancestors of metazoans calls for the extension of molecular biology data to cell physiology.
- Many data on Ca2+ signalling throughout evolution yield a quite consistent picture. The present issue of Cell Calcium presents an interim balance.