In enzymology, a low-density-lipoprotein receptor kinase (EC 2.7.11.29) is an enzyme that catalyzes the chemical reaction

ATP + [low-density-lipoprotein receptor]-L-serine ${\displaystyle \rightleftharpoons }$ ADP + [low-density-lipoprotein receptor]-O-phospho-L-serine

Thus, the two substrates of this enzyme are ATP and [[[low-density-lipoprotein receptor]-L-serine]], whereas its two products are ADP and [[[low-density-lipoprotein receptor]-O-phospho-L-serine]].

This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain oxygen atom of serine or threonine residues in proteins (protein-serine/threonine kinases). The systematic name of this enzyme class is ATP:[low-density-lipoprotein receptor]-L-serine O-phosphotransferase. Other names in common use include ATP:low-density-lipoprotein-L-serine O-phosphotransferase, LDL receptor kinase, [low-density-lipoprotein] kinase, low-density lipoprotein kinase, low-density-lipoprotein receptor kinase (phosphorylating), and STK7.

• Kishimoto A, Brown MS, Slaughter CA, Goldstein JL (1987). "Phosphorylation of serine 833 in cytoplasmic domain of low density lipoprotein receptor by a high molecular weight enzyme resembling casein kinase II". J. Biol. Chem. 262 (3): 1344–51. PMID 3100530.
• Kishimoto A, Goldstein JL, Brown MS (1987). "Purification of catalytic subunit of low density lipoprotein receptor kinase and identification of heat-stable activator protein". J. Biol. Chem. 262 (19): 9367–73. PMID 3597414.