Two distinct types of cell surface folic acid‐binding proteins in Dictyostelium discoideum

FEBS Letters

De Wit, R.J.W.¹ 

[1] Zoological Laboratory, Cell Biology and Morphogenesis Unit, University of Leiden, Kaiserstraat 63, 2311 GP Leiden, The Netherlands

关键词: Folic acid;    Deamino-folic acid;    Binding proteins;    D.discoideum;   

DOI  :  10.1016/0014-5793(82)80786-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Folic acid is degraded too fast by Dictyostelium discoideum to study binding of this ligand to cell surface binding proteins. Folate deaminase activity was inhibited in the presence of 3.3 × 10⁻⁴ M 8-azaguanine. This inhibitor enabled us to detect two folate binding proteins. One type bound folic acid and deamino-folic acid with the same affinity (K _0.5 = 3–6 × 10⁻⁷ M) and apparently negative cooperativity. Binding to only this type was observed if 8-azaguanine was omitted. The second type bound folic acid noncooperatively with K _d = 7 × 10⁻⁷ M. Deamino-folic acid did not compete even at a 1000-fold excess. This type may correspond to the chemotactic receptor.

【 授权许可】

Unknown