Immunological evidence that HMG-CoA reductase kinase-A is the cauliflower homologue of the RKIN1 subfamily of plant protein kinases.

Three different antibodies against the RKIN1 and BKIN12 gene products from rye and barley recognized the 58 kDa subunit of HMG-CoA reductase kinase-A (HRK-A) from Brassica oleracea on Western blots. HRK-A was also detected by an antipeptide antibody in enzyme-linked immunoassays, and this was competed by the peptide antigen. HRK-A was not recognized by antibodies against plant, mammalian and Saccharomyces cerevisiae relatives of RKIN1, i.e. wheat PKABA1, rat AMP-activated protein kinase and S. cerevisiae Snf1p. RKIN1/HMG-CoA reductase kinase-A are now among the first protein kinases in plants to be well characterized at both the molecular and biochemical levels.