▁ ▁Disc overy ▁and ▁classification ▁ ▁M AP 4 K 4 ▁is ▁categor ized ▁under ▁the ▁m amm al ian ▁ster ile ▁ 2 0 ▁protein ▁( Ste 2 0 p ) ▁kin ase ▁family ▁due ▁to ▁its ▁shared ▁hom ology ▁with ▁the ▁Ste 2 0 p ▁kin ase ▁found ▁in ▁bud ding ▁ye ast ▁and ▁is ▁a ▁member ▁of ▁the ▁G CK - IV ▁sub family . ▁M amm al ian ▁M AP 4 K 4 ▁was ▁initially ▁identified ▁in ▁m ice ▁as ▁a ▁kin ase ▁activ ator ▁for ▁a ▁protein ▁called ▁N ck ▁followed ▁shortly ▁by ▁identification ▁and ▁cl oning ▁of ▁the ▁human ▁orth olog ue ▁encoded ▁by ▁the ▁M AP 4 K 4 ▁gene . ▁ ▁Str ucture ▁and ▁expression ▁ ▁In ▁humans , ▁M AP 4 K 4 ▁is ▁encoded ▁by ▁the ▁M AP 4 K 4 ▁gene ▁located ▁on ▁chrom os ome ▁ 2 , ▁position ▁q 1 1 . 2 ▁and ▁consists ▁of ▁ 3 3 ▁ex ons ▁responsible ▁for ▁its ▁synth esis . ▁It ▁contains ▁approximately ▁ 1 2 0 0 ▁am ino ▁ac ids , ▁has ▁a ▁mole cular ▁mass ▁of ▁~ 1 4 0 ▁K Da . ▁and ▁its ▁orth olog ues ▁across ▁various ▁species ▁share ▁mole cular ▁and ▁struct ural ▁similar ities . ▁ ▁Struct ur ally ▁M AP 4 K 4 ▁contains ▁the ▁following ▁domains : ▁ ▁N - Term inal ▁Kin ase ▁Domain ▁ ▁Co iled - co il ▁domain ▁ ▁C - Term inal ▁H ydro ph ob ic ▁Le