In quinoa, class-1 HKT proteins load this element into bladder cells. Variations in hydrogen concentration in the brain cause acid-sensing pH sensor proteins to mainly transport this element. Paralytic shellfish poisoning occurs when alkaloids like saxitoxin block the transport of this element. (10[1])A symporter of glucose and this element called SGLT2 (10[1])is found in (10[1])proximal tubules. (10[1])Subunits of proteins that conduct this element contain six transmembrane passes and are voltage-gated. An ion of this element enters neurons during (10[1])action potential (-5[1])firing. (-5[2])Blockers for this element’s channels can be used to treat arrhythmia. Hydrolysis (-5[1])of ATP pumps three atoms of this element out of cells (10[1])against potassium. (10[2]-5[1])For 10 points, name this element found alongside chloride in table salt. ■END■ (10[4])