N00014C11C1C0889, N00014C14C1C0716), National Institutes of Health (grant no. anhydrases (CAs) in a broad range of biochemical processes have been investigated such as carboxylation or decarboxylation reactions, including photosynthesis and respiration. CAs are some of the most rapid enzymes known that facilitate the catalysis of CO2 and water to bicarbonate and protons. CA proteins can be grouped into several major distinct classes (, , and ; Hewett-Emmett and Tashian, 1996; Tripp et al., 2001) and also, – and -classes (Lane and Morel, 2000; So et al., 2004). To date, all CAs identified Vinorelbine (Navelbine) in animal systems belong to -class, whereas in plants and algae, known CAs are more diverse, belonging to the -, -, -, and -classes. In algae, a key function of CAs is in the CO2-concentrating mechanism, which concentrates inorganic carbon for efficient photosynthetic activity (Badger and Price, 2003; Spalding, 2008; Moroney et al., 2011; Rabbit Polyclonal to SPI1 Wang et al., 2011; Ludwig, 2012). In the microalga was identified to function in, but is not rate limiting for, C4 photosynthesis as found in antisense suppression analyses (von Caemmerer et al., 2004). It has been suggested that CA activity in C4 plants is near rate limiting for photosynthesis (Hatch and Burnell, 1990; Cousins et al., 2008). A recent study in maize (double-mutant plants Vinorelbine (Navelbine) were not reduced under current and elevated CO2 partial pressures but were impaired at low partial pressures (Studer et al., 2014). In C3 plants, the roles of CAs in limiting photosynthesis are less clear, but CAs do have biological roles in mitochondrial physiology (Perales et al., 2005) and function in male sterility (Villarreal et al., 2009). In addition to the roles of CAs in biochemical processes, recent research has shown that CAs function in animal CO2 signaling pathways. An CA has been identified in mice as a CO2 perception mechanism controlling the olfactory response of guanylyl cyclase D neurons (GC-D+) to CO2 that triggers an avoidance behavior (Hu et al., 2007). An inhibitor of CAs reduces the ability of rodents to detect CO2, providing pharmacological evidence that CAs function as olfactory CO2 receptors (Ferris et al., 2007; Hu et al., 2007). It was found that CO2-induced action potentials occur in nerves that connect to taste receptors (sour sensing) cells in the mouse tongue (Chandrashekar et al., 2009). When taste receptor cells in which the carbonic anhydrase4 (Car4) is expressed at the surface were ablated in the mouse tongue, the response to CO2 disappeared, indicating that CA is an essential component of the CO2 response linked with sour taste (Chandrashekar et al., 2009). In plants, CO2 signaling mechanisms control stomatal movements. Stomata in the epidermis of aerial tissues enable CO2 influx for photosynthesis (Cardon et al., 1994; DeLucia et al., 1999; Medlyn et al., 2001; Hetherington and Woodward, 2003). Guard cells that form stomatal pores have mechanisms to respond to an increase in the CO2 concentration in leaves (in guard cells using a strong guard cell promoter (Hu et al., 2010). These findings support the hypotheses that the enzymatic activities of CA1 and CA4 mediate the stomatal CO2 response and that these CAs do not function as noncatalytic CO2 receptors. Additional electrophysiological analyses showed that intracellular HCO3? ions in guard cells lead to enhanced activation of guard cell anion channels and together with the above analyses, suggest that this stomatal CO2 response Vinorelbine (Navelbine) mediated by CA1/CA4 can be perceived directly by guard cells (Xue et al., 2011). Additional findings identified GROWTH CONTROL BY ABSCISIC ACID2 (GCA2), OPEN STOMATA1 (OST1), and SLOW ANION CHANNEL-ASSOCIATED1 (SLAC1) as positive regulators (Young et al., 2006; Negi et al., 2008; Vahisalu et al., 2008; Xue et al., 2011) and the HIGH LEAF TEMPERATURE1 Vinorelbine (Navelbine) (HT1) kinase and a malate uptake transporter ATP-BINDING CASSETTE B14 (AtABCB14) as negative regulators (Hashimoto et al., 2006; Lee et al., 2008) in the.