Related Experiment Video

Updated: Jan 29, 2026

The Number e as a Limit
01:29

The Number e as a Limit

Published on: January 12, 2026

85

Recognition of DNA damage by the Rad4 nucleotide excision repair protein

Jung-Hyun Min1, Nikola P Pavletich

  • 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.

Nature
|September 21, 2007
PubMed

Insights

The xeroderma pigmentosum C (XPC) protein, Rad4, binds to damaged DNA by flipping out base pairs. This mechanism is crucial for initiating DNA repair pathways and preventing skin cancer.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Mutations in nucleotide excision repair (NER) cause xeroderma pigmentosum, a syndrome predisposing to skin cancer.
  • The xeroderma pigmentosum C (XPC) protein initiates global-genome NER by recognizing DNA lesions.
  • NER lesions are diverse, caused by UV radiation and genotoxic chemicals, and affect a single DNA strand.

Purpose of the Study:

  • To elucidate the structural mechanism by which the XPC orthologue Rad4 recognizes DNA lesions.
  • To understand how Rad4 binding initiates the NER pathway.

Main Methods:

  • X-ray crystallography was used to determine the structure of yeast Rad4 bound to DNA containing a cyclobutane pyrimidine dimer (CPD) lesion.

Main Results:

  • The crystal structure reveals Rad4 inserts a beta-hairpin into the DNA duplex, causing two base pairs to flip out.
  • Rad4 recognizes nucleotides from the undamaged strand, while the CPD-damaged nucleotides become disordered.
  • This interaction destabilizes the DNA double helix, facilitating lesion recognition.

Conclusions:

  • The findings reveal a novel mechanism for DNA damage recognition by Rad4/XPC.
  • This structural insight into lesion destabilization is key to understanding NER initiation.
  • The study provides a foundation for further research into DNA repair and cancer predisposition.

More Related Videos

Types of Limits I01:23

Types of Limits I

Published on: November 26, 2025

178
Limiting Reactant and Calculation from Reaction Stoichiometry02:27

Limiting Reactant and Calculation from Reaction Stoichiometry

70.0K

Related Concept Videos

The Number e as a Limit01:29

The Number e as a Limit

The number e is a fundamental constant in calculus, playing a central role in describing continuous change, particularly exponential growth. It is most naturally defined through its relationship with the natural logarithm, which is the inverse of the exponential function with base e. This relationship allows e to be characterized using basic principles of differentiation rather than as an arbitrary numerical constant.A key property of the natural logarithm function, ln x, is that its derivative...
85
Limits at Infinity01:24

Limits at Infinity

The function that decreases as the input becomes very large provides a clear example of how mathematical functions can behave at extreme values. When the input increases continuously, the output becomes smaller and smaller, getting closer to a particular fixed value. Although the output never actually reaches this value, it moves nearer to it without limit. This behavior is a fundamental concept in understanding how functions behave as the input grows indefinitely. The graphical representation...
320
Introduction to Limits01:30

Introduction to Limits

A limit describes the value a function approaches as its input moves closer to a particular point. Even when a function is undefined at a specific value, limits allow us to analyze its behavior near that point. This concept is fundamental in calculus and essential for understanding continuity, derivatives, and integrals.Mathematically, a function f(x) has a limit L at x = a if its values L approach x as x gets arbitrarily close to a. This is written as:This notation expresses that the function...
228
Types of Limits I01:23

Types of Limits I

Limits are a key mathematical concept for understanding how functions behave as their input approaches specific values, particularly when the function is undefined. They help reveal trends and discontinuities by examining the values a function approaches rather than its actual value.One-sided limits focus on the direction from which a value is approached. When a function behaves differently depending on whether the input approaches from the left or the right, the two one-sided limits may not...
178
Limit Laws I01:25

Limit Laws I

Limit laws provide essential tools for analyzing how functions behave as their input approaches a specific value. These laws are particularly useful when dealing with combinations of functions, provided the individual limits exist. The Sum and Difference Laws state that the limit of the sum or difference of two functions equals the sum or difference of their respective limits:The Product Law asserts that the limit of the product of two functions equals the product of their individual limits:A...
220
Limiting Reactant02:27

Limiting Reactant

The relative amounts of reactants and products represented in a balanced chemical equation are often referred to as stoichiometric amounts. However, in reality, the reactants are not always present in the stoichiometric amounts indicated by the balanced equation.
70.0K