You are here:

Biology/Carrier Proteins

Advertisement

Expert: John Locke - 9/25/2010


Question
Hello,

I know that carrier proteins have specific molecules they can transport but how
do they recognise the molecules they can transport from all the others?

Answer
Thanks for using AllExperts.

Carrier proteins recognize the molecules that they carry on the basis of shape, primarily, and partly on the basis of charge. Carrier proteins carry out most of their functions on the basis of shape: they rely upon an active site with a specific shape that fits the target molecule only. The target molecule binds to that active site with a certain affinity and is released later, either after a certain event occurs or when the affinity has decreased.

In the case of carrier proteins, the affinity is usually high when the active site faces the outside of the cell and drops when facing the inside of the cell. In this way, substances get transported from the outside to the inside of the cell and not the reverse. Active sites have two features that control the binding of particular molecule: amino acids at the active site are in a specific conformation that will physically fit only one molecule (or a small group of very similar molecules); and the amino acids at the active site may have charges that complement those on the target molecule (as you likely know, like charges repel and opposite charges attract).

This principle of active sites binding to a specific molecule is true of almost all proteins.

Biology

All Answers

Answers by Expert:

Ask Experts

Volunteer

John Locke

Expertise

I will answer all biology-related questions through the undergraduate level. I will explain unclear concepts and suggest approaches to solving problems, but would prefer not to completely solve homework problems for you. If you are completely stumped on homework, tell me what you already know and I will help you as much as possible. Please do not ask me for ideas on school research projects; part of research is determining a suitable area of investigation, and that's not a task that should be completed by someone else. Please don't simply send me your homework for solutions. If you are having difficulty after you have started an analysis, I will be happy to direct your thinking; in particular, I would prefer to not simply solve pedigrees for students, but I will be happy to assist in solving pedigrees that you have already started. If you don't understand how to analyze a pedigree, I'd highly recommend watching this video, in which a biology professor explains the basic concepts of pedigree analysis: http://www.youtube.com/watch?v=HbIHjsn5cHo

Experience

I have a BS in Bioengineering with a concentration in Chemical Engineering (which included a heavy focus on biology), and have taught biology, biochemistry, and related subjects for some time now.

Education/Credentials
BS Bioengineering, Penn State University MCAT/DAT/OAT Instructor

©2012 About.com, a part of The New York Times Company. All rights reserved.