Cloning and characterization of the Xenopus cyclin-dependent kinase inhibitor p27XIC1

Related Experiment Video

Updated: Oct 22, 2026

Reconstitution Of β-catenin Degradation In Xenopus Egg Extract
09:41

Reconstitution Of β-catenin Degradation In Xenopus Egg Extract

Published on: June 17, 2014

J Y Su1, R E Rempel, E Erikson

  • 1Howard Huhges Medical Institute, University of Colorado School of Medicine, Denver 80262, USA.

Proceedings of the National Academy of Sciences of the United States of America
|October 24, 1995
PubMed

Insights

Researchers identified Xic-1, a novel cyclin-dependent kinase (Cdk) inhibitor in Xenopus, crucial for regulating DNA synthesis. Xic-1 interacts with Cdks and PCNA, controlling cell cycle progression.

Area of Science:

  • Molecular Biology
  • Developmental Biology
  • Cell Cycle Regulation

Background:

  • Cyclin-dependent kinases (Cdks) regulate cell cycle progression.
  • Cdk inhibitors (CKIs) play critical roles in controlling cell division.
  • Understanding CKI function is vital for comprehending cell cycle control mechanisms.

Purpose of the Study:

  • To isolate and characterize a novel Cdk inhibitor from Xenopus.
  • To investigate the functional domains of the identified inhibitor.
  • To elucidate the role of this inhibitor in DNA synthesis regulation.

Main Methods:

  • Gene isolation and cloning of Xic-1 from Xenopus ovary.
  • Recombinant protein expression and purification.
  • In vitro kinase assays to assess inhibition of Xenopus Cdks.
  • DNA synthesis assays in egg extracts.

Main Results:

  • Xic-1, a 27-kDa Cdk inhibitor, was isolated from Xenopus.
  • Xic-1 shares homology with mammalian CIP1 and Kip1/Kip2.
  • N- and C-terminal domains mediate interactions with Cdks and PCNA, respectively.
  • Xic-1 inhibits Xenopus cyclin E/Cdk2, cyclin A/Cdk2, and cyclin B/Cdc2 with varying potencies.
  • N-terminal truncation specifically impacts cyclin A/Cdk2 inhibition.
  • Xic-1 inhibits DNA synthesis in egg extracts, reversible by PCNA or cyclin E/Cdk2.

Conclusions:

  • Xic-1 is a functional Cdk inhibitor in Xenopus.
  • The study suggests a role for Xic-1 in controlling DNA synthesis via cyclin E/Cdk2.
  • Xic-1 represents a key regulator in the Xenopus cell cycle, particularly in DNA replication.

More Related Videos

Functional Cloning Using a Xenopus Oocyte Expression System09:40

Functional Cloning Using a Xenopus Oocyte Expression System

Published on: January 30, 2016

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

Related Concept Videos

Positive Regulator Molecules01:45

Positive Regulator Molecules

To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated.
X-Inactivation01:58

X-Inactivation

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, one might expect females to produce twice as many of the proteins, with undesirable results.
Positive Regulator Molecules02:39

Positive Regulator Molecules

Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...