Recombinant Mouse VLDLR (Cys297) Protein, CF

VLDL R is a 130 kDa type I transmembrane protein in the LDL receptor family that plays a significant role in lipid metabolism and in nervous system development and function (1, 2). Mouse VLDL R has a 774 aa extracellular domain (ECD) (aa 25‑798) and a 54 aa cytoplasmic domain. The ECD contains eight LDLR class A repeats, three EGF‑like domains, six LDLR class B repeats, and a juxtamembrane region that is rich in O‑linked glycosylation (3, 4, 5). The cytoplasmic domain contains one NPXY internalization motif. Mouse VLDL R has at least one 105 kDa alternative splice form. This variant (termed type II VLDL R) shows an Arg substitution for aa 751‑779, and has been associated with endothelial cells (5, 6). The VLDL R expressed here corresponds to a polymorphic form that shows a Cys at position 297 of the precursor. This generates a disulfide bond in the 7^th LDL class A domain that is not present when position 297 is occupied by Ser (SwissProt # P98156). The 7^th domain is suggested to be a critical determinant of apoE binding to VLDL R (7). VLDL R is predominantly expressed in striated muscle, adipose tissue, brain, and endothelial cells lining capillaries and small arterioles (3, 4, 8, 9). VLDL R participates in the tissue uptake of fatty acids from plasma by mediating the internalization of ApoE‑containing lipoparticles (i.e. VLDL, beta‑VLDL, and chylomicron remnants) (8, 10). VLDL R binds and internalizes lipoprotein lipase (LPL) and mediates its transport from the basolateral to the lumenal face of endothelial cells (9, 11). VLDL R knockout mice are characterized by reduced LPL activity, reduced serum triglyceride clearance, and a resistance to developing obesity (10, 12, 13). VLDL R influences breast cancer cell motility by mediating the uptake of uPAR‑PAI1 complexes (9, 14). Lipoprotein accumulation via macrophage VLDL R is instrumental in promoting the formation of atherosclerotic plaques (15). In the nervous system, VLDL R and ApoE R2 interactions with reelin are critical for neuronal migration and positioning in the developing brain (16). VLDL R also functions in adult hippocampal synapse maturation, synaptic plasticity, and memory formation (17, 18). The ECD of mouse VLDL R shares 95% aa sequence identity with human and rat VLDL R. Within shared regions, mouse VLDL R shares 55% and 53% aa sequence identity with ApoE R2 and LDL R, respectively.