A type of excitatory amino acid receptor for which glutamate may be the endogenous ligand. It is named after its specific agonist ligand, kainate. The receptor is coupled to Na⁺/K⁺ channels in the cell membrane, which are opened when activated by the agonist. Activation by the agonist is indirect, through the action of G-protein, or guanine nucleotide binding protein, which acts as a transducer of information between the receptor and the ion channel. For more details on the structure and mechanism of signal transduction, see Carlson, Ch. 4; or Oxford Reference Online.

Natural selection operating indirectly on a character by favouring the relatives of the individual having that character. For example, the genes that cause a woman’s reproductive activity to be switched off at a certain stage will be favoured by natural selection if, as a result of her post-reproductive behaviour, her progeny and those of other close relatives are more likely to survive.