Yu M H, Glazer A N
J Biol Chem. 1982 Apr 10;257(7):3429-33.
The phycocyanin-containing segments of the rod substructures of Anabaena variabilis phycobilisomes consist of complexes of phycocyanin with "linker" polypeptides of 27,000 and 32,500 daltons (Yu, M.-H., Glazer, A. N., and Williams, R. C. (1981) J. Biol. Chem. 256, 13130-13136). Complexes (alpha beta)3.27,000, (alpha beta)3.32,500, (alpha beta)6.27,000, [(alpha beta)6.32,500]n, (alpha beta)6.27,000 - (alpha beta)6.32,500 were prepared, where alpha beta represents a monomer of phycocyanin, and 27,000 and 32,500 represent the 27,000- and 32,500-dalton polypeptides, respectively. Tryptic digestion of (alpha beta)3.32,500 leads to a stable (alpha beta)3.28,000 complex which does not form higher aggregates. The 32,500 polypeptide is stable to trypsin in the [(alpha beta)6.32,500]n and (alpha beta)6.27,000 - [(alpha beta)6.32,500]n=1.2 aggregates. Upon trypsin treatment of all 27,000 still assembled into higher aggregates, (alpha beta)6.21,0900 and (alpha beta)6.21,000 - (alpha beta)6.32,500. The spectroscopic properties of phycocyanin-linker polypeptide complexes were not modified by the tryptic cleavages. These results show that the 32,500 polypeptide has two distinct functional domains, a 28,000 portion necessary to the stabilization of a trimeric phycocyanin complex and a 4,500 domain which links consecutive phycocyanin hexamers in the rod substructure. The 27,000 polypeptide likewise has two distinct functional domains: a 21,000 domain stabilizes a trimeric phycocyanin complex, a 6,000 domain is exposed in all of the assembly forms examined. From these and earlier studies, it is concluded that the 6,000 domain functions in the attachment of the rod substructures to the core of the phycobilisome.
多变鱼腥藻藻胆体杆状亚结构中含藻蓝蛋白的片段由藻蓝蛋白与27000和32500道尔顿的“连接”多肽形成的复合物组成（余，M.-H.，格拉泽，A. N.，以及威廉姆斯，R. C.（1981年）《生物化学杂志》256，13130 - 13136）。制备了复合物(αβ)₃·27000、(αβ)₃·32500、(αβ)₆·27000、[(αβ)₆·32500]ₙ、(αβ)₆·27000 - (αβ)₆·32500，其中αβ代表藻蓝蛋白单体，27000和32500分别代表27000道尔顿和32500道尔顿的多肽。对(αβ)₃·32500进行胰蛋白酶消化会产生一种稳定的(αβ)₃·28000复合物，该复合物不会形成更高聚集体。在[(αβ)₆·32500]ₙ和(αβ)₆·27000 - [(αβ)₆·32500]ₙ = 1.2聚集体中，32500多肽对胰蛋白酶稳定。用胰蛋白酶处理所有仍组装成更高聚集体的27000后，会得到(αβ)₆·21000和(αβ)₆·21000 - (αβ)₆·32500。藻蓝蛋白 - 连接多肽复合物的光谱性质未因胰蛋白酶切割而改变。这些结果表明，32500多肽有两个不同的功能结构域，一个28000的部分是三聚体藻蓝蛋白复合物稳定所必需的，一个4500的结构域在杆状亚结构中连接连续的藻蓝蛋白六聚体。27000多肽同样有两个不同的功能结构域：一个21000的结构域稳定三聚体藻蓝蛋白复合物，一个6000的结构域在所有检测的组装形式中都暴露在外。从这些以及早期的研究可以得出结论，6000结构域在杆状亚结构与藻胆体核心的连接中起作用。
