Disease relevance of GORK

• Transpiration measurements on excised rosettes and intact plants (grown in hydroponic conditions or submitted to water stress) revealed that absence of GORK activity resulted in increased water consumption [1].

High impact information on GORK

• Expression of GORK dominant negative mutant polypeptides in transgenic Arabidopsis was found to strongly reduce outwardly rectifying K(+) channel activity in the guard cell membrane, and disruption of the GORK gene (T-DNA insertion knockout mutant) fully suppressed this activity [1].
• The Arabidopsis outward K+ channel GORK is involved in regulation of stomatal movements and plant transpiration [1].
• Bioassays on epidermal peels revealed that disruption of GORK activity resulted in impaired stomatal closure in response to darkness or the stress hormone abscisic acid [corrected] [1].
• Studying all shaker-like ion channel alpha-subunits, we only found the K(+) inward rectifier AtKC1 and AKT1 and the K(+) outward rectifier GORK to be expressed in this cell type [2].
• SKOR and GORK are outward-rectifying plant potassium channels from Arabidopsis thaliana [3].

Chemical compound and disease context of GORK

• Regulation of the ABA-sensitive Arabidopsis potassium channel gene GORK in response to water stress [4].

Biological context of GORK

• Here we provide direct evidence, based on reverse genetics approaches, that the Arabidopsis GORK Shaker gene encodes the major voltage-gated outwardly rectifying K(+) channel of the guard cell membrane [1].
• Based on the expression profile and the electrical properties of the root hair plasma membrane we conclude that AKT1-, ATKC- and GORK-mediated potassium transport is essential for osmoregulation and repolarization of the membrane potential in response to elicitors [5].
• Based on their electrophysiology and tissue expression patterns, AtSKOR encodes a depolarisation-activated outward-rectifying (Ca(2+)-permeable) K(+) channel (KORC) in stelar cells and AtGORK is likely to encode a KORC in the plasma membrane of other Arabidopsis root cells [6].

Anatomical context of GORK

• In agreement with the delayed outward rectifier in intact guard cells and protoplasts thereof, GORK is activated in a voltage- and potassium-dependent manner [7].
• When heterologously expressed in Xenopus oocytes the gene product of GORK mediated depolarization-activated K(+) currents [7].

Associations of GORK with chemical compounds

• The wilting hormone ABA that integrates responses to these stimuli induced GORK expression in seedlings in a time- and concentration-dependent manner and this induction was dependent on extracellular Ca2+ [4].

Other interactions of GORK

• We demonstrate that SKOR and GORK physically interact and assemble into heteromeric K(out) channels [3].
• The two inward rectifiers AKT1 and ATKC1 as well as the outward rectifier GORK dominated the root hair K(+) channel pool [5].
• In contrast to other tissues, GORK expression as well as K+(out) channel activity in guard cells is ABA insensitive, allowing the plant to adjust stomatal movement and water status control separately [4].

References