False characterization of membrane transporter type - (Dec/22/2008 )
This is a unspecific question- I am wondering why sometimes membrane transporter type may be categorically falsely characterized (like active or passive)? In some papers I was reading there were several differing papers on each side using similar kinetics studies as each other (MM kinetics studies with significant sample sizes and similar time frames (1-3 hours)). Out of the four I've looked at two are on the passive side and two the active side based on the kinetic studies (and in the case of active side, negative evidence in the form of energy depletion preventing transport, such as membrane decouplers to prevent ATP synthesis).
There are more differing views in other papers besides these four (according to the references). I am starting to be a bit curious since this appears to be more than an artifact, and I doubt so many investigators made large scale experimental errors enough to misinterpret so much. My question is: is there any previous experiences that can explain this, or is it really a series of artifacts? I am kind of new so perhaps I misinterpret the ability for this mistake to happen.
A different paper suggested a passive low-affinity transporter at higher concentrations (mM range, which the other studies were conducted in) and a high-affinity transporter at low concentrations (nM range) so I guess that is the explanation.