Frost S J, Kindberg G M, Oka J A, Weigel P H
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77555-0647.
Biochem Biophys Res Commun. 1992 Dec 30;189(3):1591-7. doi: 10.1016/0006-291x(92)90258-m.
We have previously shown (Biochemistry, 29, 10425, 1990) that hepatocytes contain intracellular specific binding sites for hyaluronan (HA). Although HA-binding activity is not dependent on divalent cations, it is increased in the presence of Ca+2. Here we report that a novel photoaffinity HA derivative (ASD-HA) crosslinks specifically to different proteins in permeable cells in the presence or absence of Ca+2. With Ca+2 present, two proteins of approximately 24 kD and 43 kD were labeled. Additionally, a broad zone of specific crosslinking was observed in the region of 40-100 kD. However, in the presence of the chelator EGTA this zone was absent and the 24 and 43 kD proteins were also not cross-linked to the HA photoaffinity derivative. In the absence of Ca+2, only a 54 kD protein was specifically labeled. The results indicate that different intracellular hepatocyte proteins are responsible for the Ca+2-independent and the Ca+2-dependent binding of HA.
我们之前已经证明（《生物化学》，第29卷，第10425页，1990年），肝细胞含有透明质酸（HA）的细胞内特异性结合位点。虽然HA结合活性不依赖于二价阳离子，但在Ca+2存在时会增强。在此我们报告，一种新型光亲和性HA衍生物（ASD-HA）在有或无Ca+2的情况下，都能与可渗透细胞中的不同蛋白质特异性交联。在有Ca+2存在时，标记出了两种分子量约为24 kD和43 kD的蛋白质。此外，在40 - 100 kD区域观察到一个广泛的特异性交联区。然而，在螯合剂EGTA存在的情况下，这个区域不存在，并且24 kD和43 kD的蛋白质也未与HA光亲和衍生物交联。在无Ca+2时，仅一种54 kD的蛋白质被特异性标记。结果表明，不同的肝细胞内蛋白质分别负责HA的Ca+2非依赖性和Ca+2依赖性结合。
