BCH 3125 Lecture Notes - Lecture 2: Ultrasensitivity, Cooperative Binding, Conformational Change
24 Sep 2017
School
Department
Course
Professor
Document Summary
Cells continually make decisions that affect how they respond to their environment. The decision-(cid:373)aki(cid:374)g (cid:272)ir(cid:272)uits i(cid:374) (cid:272)ells typi(cid:272)ally (cid:272)o(cid:374)sist of protei(cid:374)s that pro(cid:272)ess (cid:862)i(cid:374)puts(cid:863) a(cid:374)d ge(cid:374)erate (cid:862)outputs(cid:863: usually at the heart of each processing unit is an interaction between a protein and a ligand. Graded response: an output function that depends on the input a hyperbolic fashion, as in a simple binding equilibrium, is known as a graded or linear response. In such a response, the output switches from 10% to 90% of the maximum response over a 100-fold change in input strength. Ultra-sensitivity: a dimeric protein with two binding sites can display ultra-sensitivity if the confirmations of the two binding sites are coupled. Ligand binding to one site causes an allosteric change in the other site, affecting the affinity for the ligand at the unoccupied sites: this ligand binding to such a system is said to be cooperative.
