Muramatsu H, Inui T, Kimura T, Sakakibara S, Song X J, Maruta H, Muramatsu T
Department of Biochemistry, Nagoya University School of Medicine, Japan.
Biochem Biophys Res Commun. 1994 Sep 15;203(2):1131-9. doi: 10.1006/bbrc.1994.2300.
Midkine is a 13kDa heparin-binding polypeptide rich in basic amino acids and cysteine and has neurite outgrowth, neuronal cell survival and other activities. We used chemically synthesized MK half molecules as well as recombinant MK deficient in N-terminal and C-terminal sequences to localize its active regions. The principal and conformation-dependent heparin-binding site was found in the C-terminal half. On the other hand, 13 amino acid residues in the C-terminal end were responsible for the MK antigenicity. The C-terminal half, but not the N-terminal half, had potent neurite outgrowth activity. However, in contrast to the whole molecule, the C-terminal half could not support the survival of embryonic brain neurons.
中期因子是一种富含碱性氨基酸和半胱氨酸的13kDa肝素结合多肽，具有促进神经突生长、神经元细胞存活等活性。我们使用化学合成的中期因子半分子以及缺乏N端和C端序列的重组中期因子来定位其活性区域。主要的且依赖构象的肝素结合位点位于C端半分子。另一方面，C端的13个氨基酸残基负责中期因子的抗原性。C端半分子具有强大的神经突生长活性，而N端半分子则没有。然而，与整个分子不同的是，C端半分子不能支持胚胎脑神经元的存活。
