The Biology Project > Cell Biology > Cell Signaling > Problem Set

Cell Signaling Problem Set

Problem 2: Signal Responses I

Tutorial to help answer the question

Signaling between cells usually results in the activation of protein _______.

A. lipases
B. kinases
C. proteases
D. nucleases


Activation of protein kinases

Protein Kinase Cascade

Many classes of receptor bind their ligand and activate protein kinases inside the cell. Kinases transfer phosphate to specific target proteins causing a cell response. Activation frequently leads to a protein kinase cascade, resulting in the rapid amplification of extra-cellular signals. Some important concepts are:

    1. Two types of cells may have the same receptor but have different target proteins for the kinases. This allows the same signal and receptor to cause different responses.
    2. The cascade can lead to rapid amplification of the signal, dramatically speeding up a cell response.
    3. Responses to signals by phosphate transfers must be reversible. Phosphatases that remove phosphates are one example of a specific mechanism to reverse a signal response.
Problem 2 | Answer | Problem 3

The Biology Project > Cell Biology > Cell Signaling > Problem Set

The Biology Project
University of Arizona
May 2, 2002
Contact the Development Team
All contents copyright © 2002. All rights reserved.

The Biology Project Cell Biology