ATPK1 (P70 RIBOSOMAL S6 KINASE); kinase/ protein binding. Identical to Serine/threonine-protein kinase AtPK1/AtPK6 (ATPK1) [Arabidopsis Thaliana] (GB:P42818); similar to ATPK19 (ARABIDOPSIS THALIANA PROTEIN KINASE 19), kinase [Arabidopsis thaliana] (TAIR:AT3G08720.1); similar to ATPK19 (ARABIDOPSIS THALIANA PROTEIN KINASE 19), kinase [Arabidopsis thaliana] (TAIR:AT3G08720.2); similar to putative pp70 ribosomal protein S6 kinase [Avena sativa] (GB:CAA56313.1); similar to Os03g0334000 [Oryza sativa (japonica cultivar-group)] (GB:NP_001050027.1); similar to ribosomal protein S6 kinase [Zea mays] (GB:NP_001105237.1); contains InterPro domain Ser