VLDL R is a 105 kD type I integral membrane protein that belongs to the LDL receptor family. It plays a significant role in lipid metabolism and in nervous system development and function. 1,2 Mouse VLDL R has a 770 amino acid (aa) extracellular domain (ECD) and a 54 aa cytoplasmic region. The ECD contains eight LDLR class A repeats, three EGF-like repeats, six LDLR class B repeats, and a juxtamembrane region that is rich in O-linked glycosylation. 3,4 The cytoplasmic domain contains one NPXY internalization motif. VLDL R is predominantly expressed in striated muscle, adipose tissue, brain, and endothelial cells lining capillaries and small arterioles. 3-6 VLDL R participates in the tissue uptake of fatty acids from plasma by mediating the internalization of ApoE-containing lipoparticles (i.e. VLDL, β-VLDL, and chylomicron remnants). 5,7 VLDL R binds and internalizes lipoprotein lipase (LPL) and mediates its transport from the basolateral to the lumenal face of endothelial cells. 6,8 VLDL R knockout mice are characterized by reduced LPL activity, reduced serum triglyceride clearance, and a resistance to developing obesity. 7,9,10 VLDL R influences breast cancer cell motility by mediating the uptake of uPAR-PAI1 complexes. 6,11 Lipoprotein accumulation via macrophage VLDL R is instrumental in promoting the formation of atherosclerotic plaques. 12 In the nervous system, VLDL R and ApoE R2 interactions with reelin are critical for neuronal migration and positioning in the developing brain. 13 VLDL R also functions in adult hippocampal synapse maturation, synaptic plasticity, and memory formation. 14,15 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.
Source: Mouse VLDLR (Met 1-Ala 798), HHHHHHHHHH; A DNA sequence encoding the extracellular domain of mouse VLDLR (Met 1-Ala 798; Accession # P98156) (Oka, K. et al., 1994, Eur. J. Biochem. 224(3): 975-982) was fused to a polyhistidine tag at the carboxy-terminus. The chimeric protein was expressed in a mouse myeloma cell line, NS0.
Molecular Mass: Based on N-terminal sequencing, the recombinant mouse VLDLR starts at Thr 25 and has a calculated molecular mass of approximately 86.4 kD. As a result of glycosylation, the recombinant mouse VLDLR migrates as an approximately 125-135 kD protein in SDS-PAGE under reducing conditions.
Endotoxin Level: < 1.0 EU per 1 μg of the receptor as determined by the LAL method.
Activity: Measured by its ability to bind microtiter well bound rhApoE3 in a functional ELISA. The estimated KD for this binding is < 1 nM.
Reconstitution: It is recommended that sterile PBS be added to the vial to prepare a working stock solution of no less than 100ug/ml. The carrier-free protein should be used immediately upon reconstitution to avoid losses in activity due to non-specific binding to the inside surface of the vial. For long term, storage as a dilute solution, a carrier protein (e.g. 0.1% HSA or BSA) should be added to the vial.
Storage and Stability: Lyophilized samples are stable for up to twelve months at -20°C. Upon reconstitution, this protein, in the presence of a carrier protein, can be stored under sterile conditions at 2°-8° C for one month or at -20°C in a manual defrost freezer for three months without detectable loss of activity. Avoid repeated freeze-thaw cycles.
