Talk:Carrier protein
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Article Grading: The following comments were left by the quality and importance raters: (edit · history · refresh · how to use this template) This page states that carrier proteins move substances DOWN (i.e., along) their concentration gradient by facilitated diffusion and ACTIVE TRANSPORT. This is incorrect. Whenever something is moved DOWN its concentration gradient, there is no energy requirement; it is a spontaneous process. Active transport is used to transport a substance AGAINST its concentration gradient. Facilitated diffusion is a passive, albeit protein-mediated process that moves a substance down its gradient. I am going to delete "active transport" from this entry. I am pretty sure that carrier proteins do not require an input of energy, but if they do then "active transport" should be reinstated and "passive transport" deleted. |
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At present this states the following:
Embedded in the cell membrane these proteins transport substances against the concentration gradient out of or into the cell. Therefore carrier proteins conduct facilitated diffusion and active transport. Each carrier protein is designed to recognize one substance or one group of very similar substances only.
It should be noted that this must be wroong in some way as facilitated diffusion does not occur against a concentration gradient but with it!
[edit] Cat
Would it be appropriate to put this article into Category:transport proteins, or is there a difference between carrier and transport proteins? If not, should this article be merged with transport protein? Thanks, delldot | talk 07:18, 9 January 2007 (UTC)
According to the IUPAC Compendium of Chemical Terminology, 2004, the term "carrier protein" has several meanings: 1. Protein to which a specific ligand or hapten is conjugated. 2. Unlabeled protein introduced into an assay at relatively high concentrations which distributes in a fractionation process in the same manner as labeled protein analyte, present in very low concentrations. 3. Protein added to prevent non-specific interaction of reagents with surfaces, sample components, and each other. 4. Protein found in cell membranes, which facilitates transport of a ligand across the membrane. The present article focuses only on definition #4, but should be amended in some way to reflect the various meanings rather than focusing on just one. Anyone know how to handle this situation? bwbrian (talk) 16:23, 8 May 2008 (UTC)
