Hik29 (slr0311) is a sensor histidine kinase from Synechocystis sp. PCC 6803. The antibody raised against Hik29 (molecular weight about 80 kDa) crossreacts with the protein of similar molecular weight in higher plant chloroplasts. According to sequence homology Hik29 shows high homology to serine-/threonine protein kinases in Arabidopsis: At5g49470 and At1g67890. The analysis of protein sequence in silico did not reveal any chloroplast-targeted transit peptides in these Arabidopsis proteins.