Effects of
Induced Deletion of Repeats in Binding Domain of the VLDL Receptor on Its
Ligand-binding Capacity
LIU Zhi-Guo, QU Shen*, FENG
Ning, ZONG Yi-Qiang, DENG Yao-Zu, FENG Zong-Chen
( Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science and
Technology, Wuhan 430030, China )
Abstract The
ligand-binding domain of the very low-density lipoprotein receptor (VLDL-R)
contains eight cysteine-rich repeat sequences that have been postulated as
ligand-binding sites. This is obviously different from that of low-density
lipoprotein receptor (LDL-R) that includes seven similar repeats. To make clear
the contribution of these repeats to ligand-binding and to explore the reason
of both receptors’ ligand-binding characteristic, the VLDL-R recombinants lacking different repeat(s) were
constructed by oligonucleotide-directed mutagenesis and transfected into ldl-A7
cell. Ligand-binding results showed that repeat 1 and repeat 2 were the most
important in binding with apoE-rich lipoprotein(VLDL and β-VLDL). Repeat 3 and
repeat 6 also important for binding VLDL. The results also showed that VLDL-R
lacking LBR7 retained partly LDL-R ligand-binding properities. It suggests that
LBR7 in VLDL-R may responsible for both receptors’ ligand-binding properties
differences.
Key words VLDL receptor; lipoprotein;
oligonucleotide-directed mutagenesis
*Corresponding author: Tel, 86-27-83692624； Fax， 86-27-83692608； e-mail,[email protected]