Given an abstract from a research paper, your task is to identify and label relationships between chemical compounds and genes mentioned in the abstract.

The relationship type must be one of ['DOWNREGULATOR', 'SUBSTRATE', 'INDIRECT-REGULATOR', 'PART-OF', 'MODULATOR-ACTIVATOR', 'REGULATOR', 'INHIBITOR', 'COFACTOR', 'UPREGULATOR', 'ACTIVATOR', 'ANTAGONIST', 'NOT', 'INDIRECT-DOWNREGULATOR', 'SUBSTRATE_PRODUCT-OF', 'INDIRECT-UPREGULATOR', 'AGONIST', 'PRODUCT-OF', 'MODULATOR', 'DIRECT-REGULATOR', 'UNDEFINED', 'AGONIST-INHIBITOR', 'AGONIST-ACTIVATOR', 'MODULATOR-INHIBITOR'].

Please format your output as a JSON array. Each entry in the array should express a single relation, formatted as ["<Entity_A>", "<RELATION_A_B>", "<Entity_B>"]. If no relations can be found, please output an empty JSON array [].

Abstract:

TWIK-2, an inactivating 2P domain K+ channel. We cloned human and rat TWIK-2 and expressed this novel 2P domain K (+) channel in transiently transfected COS cells. TWIK-2 is highly expressed in the gastrointestinal tract, the vasculature, and the immune system. Rat TWIK-2 currents are about 15 times larger than human TWIK-2 currents, but both exhibit outward rectification in a physiological K (+) gradient and mild inward rectification in symmetrical K (+) conditions. TWIK-2 currents are inactivating at depolarized potentials, and the kinetic of inactivation is highly temperature-sensitive. TWIK-2 shows an extremely low conductance, which prevents the visualization of discrete single channel events. The inactivation and rectification are intrinsic properties of TWIK-2 channels. In a physiological K (+) gradient, TWIK-2 is half inhibited by 0.1 mm Ba (2 +), quinine, and quinidine. Finally, cysteine 53 in the M1P1 external loop is required for functional expression of TWIK-2 but is not critical for subunit self-assembly. TWIK-2 is the first reported 2P domain K (+) channel that inactivates. The base-line, transient, and delayed activities of TWIK-2 suggest that this novel 2P domain K (+) channel may play an important functional role in cell electrogenesis.
[["Ba (2 +)", "INHIBITOR", "TWIK-2"], ["cysteine", "PART-OF", "TWIK-2"], ["cysteine", "PART-OF", "M1P1 external loop"], ["quinine", "INHIBITOR", "TWIK-2"], ["quinidine", "INHIBITOR", "TWIK-2"]]