WNK4, Human (With-No-Lysine Kinase 4) (Control Peptide)

A 13-aa peptide sequence, mapping at the middle (around ~650-aa) region of human WNK-4 . Protein kinases represent a superfamily of over 400 members that share a catalytic domain of 250-300 amino acids. A conserved lysine, in subdomain II of the catalytic core of all 390 protein kinases, anchors a and b phosphoryl groups of ATP. The catalytic domain of WNK (With No K=Lysine) kinases contains all invariant residues, except for this lysine residue. There are 4 (identified) WNK genes (WNK1, WNK2, WNK3 and WNK4) in human (h) and rat (r). The hWNK kinases exhibit ~30% seq identity and 50% seq homology to human Mitogen Activated Protein kinases (MAPK) STK2, PAK2, MEKK3, PAK3 and Raf-1. The mutation in genes expressing WNK1 (chromosome 12p13.3) and WNK4 (chromosome 17q) causes Pseudohypoaldosteronism type II (PHAII), an autosomal disorder featuring hypertension, hyperkalemia (high serum K+ level), normal/elevated aldosterone level, increased renal salt absorption, and impaired K+ and H+ excretion. , WNK4 (human 1243-aa, 17q21) is a Ser-Thr kinase in which the conserved catalytic lysine is replaced by a cystine but another lysine residue in subdomain I confers the kinase activity. WNK4 () is 76% identical to WNK1 in kinase domain. WNK4 is expressed predominantly in kidney, colon and skin. WNK4 localize to the distal convoluted tubule (DCT) and cortical collecting duct (CCD), that play a key role in salt, water, K+ and pH homeostasis. WNK4 is present exclusively in the intracellular tight junctions in DCT and in both cytoplasm and tight junctions in CCD. In DCT, salt reabsorption is mediated by the electroneutral Na-Cl cotransporter. In the CD, Na+ is reabsorbed by the epithelial sodium channel (ENaC) providing the electrical diving force for K+ and H+ secretion. Considering the PHAII-features, WNK4 possibly, increases the chloride conductance in CD, thereby increasing salt reabsorption and intravascular volume, while concomitantly diminishing K+ and H+ secretion. Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with sterile buffer or ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.