CCNH Antibody

Introduction to CCNH and Cyclin H

Cyclin H is a protein encoded by the CCNH gene in humans and belongs to the highly conserved cyclin family. These proteins are characterized by their dramatic periodicity in abundance throughout the cell cycle, functioning primarily as regulators of cyclin-dependent kinase (CDK) kinases . Cyclin H forms a complex with CDK7 kinase and the ring finger protein MAT1, creating what is known as the CDK-activating kinase (CAK) complex . This complex plays a crucial role in cell cycle regulation by phosphorylating CDK2 and CDC2 kinases .

Beyond its role in cell cycle control, Cyclin H is also a component of the TFIIH basal transcription factor complex and RNA polymerase II protein complexes . This dual functionality establishes an important link between basal transcription control and cell cycle machinery, making Cyclin H a protein of significant research interest . Unlike other cyclins whose expression varies throughout the cell cycle, Cyclin H maintains relatively constant expression and activity levels throughout the cell cycle .

Types of CCNH Antibodies

CCNH antibodies are available in multiple formats, each with specific characteristics suitable for different research applications. These antibodies can be broadly categorized into monoclonal and polyclonal varieties, each offering distinct advantages.

Monoclonal CCNH Antibodies

Monoclonal antibodies against CCNH, such as the mouse anti-human monoclonal antibody (clone PAT3G6AT), are derived from hybridization of mouse F0 myeloma cells with spleen cells from BALB/c mice immunized with recombinant human CCNH . These antibodies typically recognize specific epitopes of the CCNH protein, offering high specificity for particular regions. Monoclonal antibodies are characterized by their homogeneity and consistency between batches, making them excellent tools for standardized experiments .

Polyclonal CCNH Antibodies

Polyclonal antibodies to CCNH, often raised in rabbits, recognize multiple epitopes of the target protein, which can provide stronger detection signals through binding to different sites on the antigen . These antibodies are typically generated using recombinant proteins or specific peptide sequences from human CCNH as immunogens . Polyclonal antibodies detect endogenous levels of total Cyclin H protein and can often recognize the protein across multiple species, including human, mouse, and rat samples .

Molecular Structure and Properties

CCNH antibodies are manufactured with specific physical and chemical properties optimized for research applications. Their structure and formulation significantly influence their functionality and application scope.

Physical Appearance and Formulation

Most commercially available CCNH antibodies are supplied as sterile filtered colorless solutions . They are commonly formulated in phosphate-buffered saline (PBS) with preservatives and stabilizers such as sodium azide and glycerol . For example, certain monoclonal CCNH antibodies are formulated at 1mg/ml in PBS (pH 7.4) with 10% glycerol and 0.02% sodium azide , while some polyclonal variants are supplied at similar concentrations in PBS without Mg²⁺ and Ca²⁺, containing 150mM NaCl, 0.02% sodium azide, and 50% glycerol .

Antibody Class and Purification Methods

Monoclonal CCNH antibodies are typically mouse IgG2b heavy chain with kappa light chain . Purification methods vary depending on the manufacturer but commonly involve protein-A affinity chromatography for both monoclonal and polyclonal antibodies . This purification process ensures high specificity and minimal cross-reactivity in research applications.

Functions and Biological Significance of Cyclin H

Understanding the biological functions of Cyclin H provides important context for the applications of CCNH antibodies in research. Cyclin H participates in multiple critical cellular processes that make it a valuable research target.

Role in Cell Cycle Regulation

Cyclin H regulates CDK7, the catalytic subunit of the CAK enzymatic complex . This complex activates several cyclin-associated kinases including CDK1, CDK2, CDK4, and CDK6 through threonine phosphorylation, which is essential for proper cell cycle progression . Unlike other cyclins that show fluctuations in abundance throughout different cell cycle phases, Cyclin H maintains relatively constant expression and activity throughout the cell cycle, suggesting a regulatory role that extends beyond typical cyclin functions .

Function in Transcriptional Regulation

Beyond cell cycle control, Cyclin H plays a crucial role in transcriptional processes. When the CAK complex associates with the core-TFIIH basal transcription factor, it activates RNA polymerase II by phosphorylating the C-terminal domain (CTD) of its large subunit (POLR2A) . This phosphorylation enables RNA polymerase II to escape from the promoter and proceed with transcript elongation . This dual functionality in both cell cycle regulation and transcription establishes Cyclin H as a critical link between these fundamental cellular processes.

The table below summarizes the key functional aspects of Cyclin H:

Applications in Research

CCNH antibodies serve as versatile tools in molecular and cellular research, with applications spanning several experimental methodologies.

Western Blot Analysis

Western blotting represents one of the primary applications for CCNH antibodies, allowing researchers to detect and analyze Cyclin H protein in cell and tissue extracts . The recommended starting dilution for Western blot analysis is typically 1:1000, though optimal concentrations may vary between different antibody preparations and experimental conditions . Western blot validation data shows that CCNH antibodies can effectively detect the protein in extracts from various cell lines .

Immunohistochemistry and Immunofluorescence

CCNH antibodies are also employed in immunohistochemistry (IHC) and immunofluorescence (IF) applications to visualize the spatial distribution of Cyclin H within cells and tissues . Immunofluorescence analysis using CCNH antibodies has been documented in HeLa cells, with nuclear localization of Cyclin H confirmed through co-staining with DAPI . These applications provide valuable insights into the subcellular localization and expression patterns of Cyclin H in different cell types and tissues.

ELISA and Other Immunoassays

Enzyme-Linked Immunosorbent Assay (ELISA) represents another important application for CCNH antibodies . These assays enable quantitative measurement of Cyclin H protein levels in various biological samples. Additional immunoassays utilizing CCNH antibodies include immunoprecipitation and chromatin immunoprecipitation, though specific protocols and validation data may vary between different antibody preparations.

Temperature Considerations

Storage recommendations typically suggest keeping CCNH antibodies at -20°C for long-term preservation . For periods up to one month, many CCNH antibodies can be stored at 4°C without significant loss of activity . Regardless of storage temperature, it is crucial to prevent freeze-thaw cycles that can degrade antibody quality and functionality .

CCNH antibodies demonstrate varying degrees of cross-reactivity between species. Many commercially available antibodies react with human, mouse, and rat Cyclin H proteins , though the specificity and sensitivity may vary. This cross-reactivity information is crucial for researchers working with animal models or cell lines from different species.

Validated Applications and Dilutions

Each CCNH antibody undergoes validation for specific applications, with recommended dilutions established through optimization experiments. The table below summarizes typical applications and recommended dilutions for CCNH antibodies:

Validation Data

Validation experiments for CCNH antibodies typically include Western blot analysis of various cell lines, which demonstrates the antibody's ability to detect the expected 37 kDa Cyclin H protein . Immunofluorescence validation in HeLa cells shows predominantly nuclear localization, consistent with Cyclin H's known functions in transcription and cell cycle regulation . These validation data provide essential information about antibody performance in different experimental contexts.