Cumsky M G, Zusman D R
J Biol Chem. 1981 Dec 10;256(23):12596-9.
The nature of the receptor for myxobacterial hemagglutinin (MBHA) on the outer surface of Myxococcus xanthus was investigated by studying the binding of 125I-MBHA to vegetative and developmental cells. The amount of binding and hence the number of binding sites/cell appeared to increase 4-fold during development to 2.1 X 10(4) sites/cell. Furthermore, the apparent association constant (Ka) for MBHA increased 3-fold to 3 X 10(7) M-1. Fetuin, a glycoprotein which binds MBHA, blocked the binding of 125I-MBHA to vegetative cells but not developmental cells. Thus, the MBHA binding sites from developmental cells clearly differ from the vegetative binding sites. The Ka for MBHA binding to sheep erythrocytes (3.5 X 10(6) M-1) was an order of magnitude lower than that of developmental M. xanthus cells. The erythrocyte binding sites are also much more sensitive to concanavalin A inhibition than the M. xanthus sites.
通过研究125I标记的粘细菌血凝素（MBHA）与黄色粘球菌营养细胞和发育细胞的结合情况，对MBHA在黄色粘球菌外表面的受体性质进行了研究。在发育过程中，结合量以及每个细胞上结合位点的数量似乎增加了4倍，达到2.1×104个位点/细胞。此外，MBHA的表观缔合常数（Ka）增加了3倍，达到3×107 M-1。胎球蛋白是一种能结合MBHA的糖蛋白，它能阻断125I-MBHA与营养细胞的结合，但不能阻断与发育细胞的结合。因此，发育细胞上的MBHA结合位点与营养细胞的结合位点明显不同。MBHA与绵羊红细胞结合的Ka（3.5×106 M-1）比发育中的黄色粘球菌细胞低一个数量级。红细胞结合位点对伴刀豆球蛋白A抑制的敏感性也比黄色粘球菌位点高得多。
