Abstract
Purpose: :
To explore the binding between lens membrane intrinsic protein (MIP26) and crystallins.
Methods: :
A mammalian two–hybrid system was used to assay the protein–protein interactions. Human lens WT and fragment (225–263) MIP26 genes were cloned into the DNA binding domain vector pM, and crystallins (αA–, αB–, ßB2–, and γC–crystallin) were cloned into the transcript activation domain vector pVIP16. Along with a reporter vector, pG5SEAP, they were cotransfected into HeLa cells. Protein–protein interactions were detected by the expression of the reporter gene, and measured in terms of the secreted alkaline phosphatase (SEAP) activity.
Results: :
Little SEAP activity was detected between WT MIP26 and crystallins but increased appreciably between MIP(225–263) fragment and crystallins. There is, however, not much difference in activities among the crystallins. The congenital cataract crystallin mutations, R116CαA, R120G αB, Q155* ßB2, and T5P γC, asserted different effects on the interactions.
Conclusions: :
There are interactions between MIP26 and crystallins, which may play an important role in the lens fiber structure and function.
Keywords: protein structure/function • cataract • proteins encoded by disease genes