Rasmussen L K, Ellgaard L, Jensen P H, Sørensen E S
Protein Chemistry Laboratory, University of Aarhus, Denmark.
J Protein Chem. 1999 Jan;18(1):69-73. doi: 10.1023/a:1020699416873.
The 39-kDa receptor-associated protein (RAP) is an intracellular glycoprotein that interacts with hitherto unknown sites in several members of the low-density-lipoprotein receptor gene family. Upon binding to these receptors, RAP inhibits all ligand interactions with the receptors. In the present study, the transglutaminase-catalyzed incorporation of radioactively labeled putrescine and a dansylated glutamine-containing peptide into human RAP has been studied. The results indicate the presence of both glutamine and lysine residues in RAP, accessible for transglutaminase cross-linking. Moreover, enzymatic digestion followed by sequence analysis of radiolabeled fractions demonstrated that Gln261 acts as the amine acceptor site. This residue is located in the third domain of RAP and is conserved among the RAP interspecies homologues. Insertion of a reporter group into the protein could prove useful to assess ligand/receptor interactions.
39 kDa受体相关蛋白（RAP）是一种细胞内糖蛋白，它能与低密度脂蛋白受体基因家族中几个成员迄今未知的位点相互作用。与这些受体结合后，RAP会抑制所有配体与受体的相互作用。在本研究中，已对转谷氨酰胺酶催化的放射性标记腐胺和含丹磺酰化谷氨酰胺的肽掺入人RAP的情况进行了研究。结果表明RAP中同时存在谷氨酰胺和赖氨酸残基，可用于转谷氨酰胺酶交联。此外，酶消化后对放射性标记组分进行序列分析表明，Gln261作为胺受体位点。该残基位于RAP的第三个结构域中，在RAP种间同源物中保守。将报告基团插入该蛋白可能有助于评估配体/受体相互作用。
