CTF4 Antibody

Introduction

The CTF4 antibody is a specialized immunological reagent designed to detect and study the eukaryotic replication factor CTF4 (Chromosome Transmission Fidelity 4), also known as WDHD1 (WD Repeat and HMG-Box DNA Binding Protein 1). CTF4 is a conserved protein critical for DNA replication and genome stability, functioning as a structural component of the replisome progression complex (RPC). This antibody enables researchers to investigate CTF4’s role in replication fork dynamics, sister chromatid cohesion, and DNA repair mechanisms.

Structure and Function of CTF4

CTF4 exists as a homotrimer, forming a platform that bridges the CMG (Cdc45/Mcm2-7/GINS) helicase complex with DNA polymerase α (Pol α) . Its C-terminal domain (CTD) contains a WD40 motif that mediates interactions with replication factors, including:

• GINS complex: Facilitates helicase activity .

• Pol α: Stabilizes replication fork progression .

• Chl1 helicase: Links replication to sister chromatid cohesion .

Epitope Specificity

CTF4 antibodies typically target regions within the CTD, including the WD40 domain responsible for binding replication partners . Commercial antibodies (e.g., rabbit polyclonal) are validated for specificity via Western blot and immunoprecipitation .

Western Blot and Immunoprecipitation

Used to analyze CTF4 recruitment to replication forks and its interaction with RPC components . For example, studies employing anti-CTF4 antibodies revealed destabilization of Pol α at replication forks in ctf4Δ mutants .

ChIP and Chromatin Studies

Employed to map CTF4 binding at replication origins and monitor cohesion establishment. ChIP-qPCR assays demonstrated CTF4’s role in recruiting Chl1 helicase to early-firing origins .

Immunohistochemistry

Localized CTF4 expression in nuclei of dividing cells, with high expression in tissues like the appendix and cervix .

Replication Fork Dynamics

• CTF4 stabilizes Pol α at replication forks, preventing stalling .

• Its absence triggers replication checkpoint activation and genome instability .

Cohesion Establishment

CTF4 recruits Chl1 helicase to replication forks, enabling cohesin deposition . Structural studies (X-ray crystallography) revealed CTF4’s trimeric structure facilitates simultaneous binding of GINS, Pol α, and Chl1 .

Conservation Across Species

Human CTF4 (hCtf4) interacts with the CMG complex to support helicase activity, as demonstrated in in vitro assays .

Table 2: Key Research Insights Using CTF4 Antibodies