InterPro domain: IPR030183

This entry represents a family of S-type (slow current) anion channels that in Arabidopsis consists of SLAC1 (SLOW ANION CHANNEL-ASSOCIATED 1, At1g12480) and SLAC1-homologue proteins 1-4 (SLAH1-4). They have in common their plasma membrane localisation, but show distinct tissue-specific expression patterns. They are distant homologues of bacterial and fungal C4-dicarboxylate transporters [ 1 ].

SLAC1 is localised specifically to the plasma membrane of guard cells [ 2 ]. It mediates CO2 sensitivity and is essential for stomatal closure in response to various endogenous and environmental stimuli [ 2 , 3 , 4 ], such as abscisic acid, ozone, light/dark transitions, humidity change, calcium ions, hydrogen peroxide and nitric oxide [ 5 ]. It also functions as an essential negative regulator of inward potassium channels in guard cells.

1. CO2 regulator SLAC1 and its homologues are essential for anion homeostasis in plant cells. Nature 452, 483-6
2. Mutations in the SLAC1 anion channel slow stomatal opening and severely reduce K+ uptake channel activity via enhanced cytosolic [Ca2+] and increased Ca2+ sensitivity of K+ uptake channels. New Phytol. 197, 88-98
3. S-type Anion Channels SLAC1 and SLAH3 Function as Essential Negative Regulators of Inward K+ Channels and Stomatal Opening in Arabidopsis. Plant Cell 28, 949-955
4. Coordinating the overall stomatal response of plants: Rapid leaf-to-leaf communication during light stress. Sci Signal 11
5. SLAC1 is required for plant guard cell S-type anion channel function in stomatal signalling. Nature 452, 487-91