ations ▁of ▁stop ▁cod ons ▁affect ▁the ▁coding ▁part ▁and ▁its ▁length ▁var ies ▁between ▁ 2 , 0 5 5 ▁and ▁ 2 , 1 9 0 ▁ ▁nucle ot ide ▁pairs . ▁Gene ▁polym orphism ▁between ▁species ▁is ▁much ▁more ▁diverse ▁than ▁the ▁in tras pec ific ▁polym orphism ▁of ▁la ct o fer rin . ▁There ▁are ▁differences ▁in ▁am ino ▁acid ▁sequences : ▁ 8 ▁in ▁H omo ▁s api ens , ▁ 6 ▁in ▁Mus ▁mus cul us , ▁ 6 ▁in ▁Cap ra ▁h irc us , ▁ 1 0 ▁in ▁Bos ▁t aur us ▁and ▁ 2 0 ▁in ▁Sus ▁sc ro fa . ▁This ▁variation ▁may ▁indicate ▁functional ▁differences ▁between ▁different ▁types ▁of ▁la ct o fer rin . ▁ ▁In ▁humans , ▁la ct o fer rin ▁gene ▁L TF ▁is ▁located ▁on ▁the ▁third ▁chrom os ome ▁in ▁the ▁loc us ▁ 3 q 2 1 - q 2 3 . ▁In ▁ox en , ▁the ▁coding ▁sequence ▁consists ▁of ▁ 1 7 ▁ex ons ▁and ▁has ▁a ▁length ▁of ▁about ▁ 3 4 , 5 0 0 ▁ ▁nucle ot ide ▁pairs . ▁Ex ons ▁of ▁the ▁la ct o fer rin ▁gene ▁in ▁ox en ▁have ▁a ▁similar ▁size ▁to ▁the ▁ex ons ▁of ▁other ▁gen es ▁of ▁the ▁transfer rin ▁family , ▁whereas ▁the ▁sizes ▁of ▁intr ons ▁differ ▁within ▁the ▁family . ▁ ▁Similar ity ▁in ▁the ▁size ▁of ▁ex ons ▁and ▁their ▁distribution ▁in ▁the ▁domains ▁of ▁the