The component of a membrane consisting of the gene products and protein complexes having at least some part of their peptide sequence embedded in the hydrophobic region of the membrane. [GOC:dos, GOC:go_curators]
GO:0000155
phosphorelay sensor kinase activity
GO:0004673
protein histidine kinase activity
Catalysis of the reaction: ATP + protein L-histidine = ADP + protein phospho-L-histidine. [EC:2.7.13.3, GOC:mah]