Provided herein are tetravalent antigen binding complexes having agonist activity for a cell surface receptor. In some embodiments, the complexes comprise binding specificities for multiple epitopes of the same cell surface receptor. Further provided herein are nucleic acids, vectors, host cells, pharmaceutical compositions, and methods of production related thereto.本文中提供對細胞表面受體具有促效活性之四價抗原結合複合物。在一些實施例中,該等複合物包含對相同細胞表面受體之多個抗原決定基的結合特異性。本文中進一步提供核酸、載體、宿主細胞、醫藥組合物及與其相關之製造方法。