On the role of diffusible binding partners in modulating the transport and concentration of proteins in tissues

Abstract

Here a reactive-diffusion transport model is used to demonstrate two previously undescribed functional roles for diffusible binding partners in the transport of molecules into tissues. The uptake of the insulin-like growth (IGF) and its binding partner the IGF binding protein (IGFBP3) into cartilage is used a specific tissue example to demonstrate a general principal. First, we show that reversible binding between free protein (IGF) and its diffusible binding partner (free IGFBPs) increases the rate of protein uptake into the tissue. Second, selective degradation of the binding partner can increase the transient and steady state free protein in tissues, well above the concentration at the so..