Recombinant Human Histone H1.2 Protein: Research Guide

Recombinant Human Histone H1.2 Protein is a purified linker histone essential for higher-order chromatin compaction and widely used as a defined research reagent in epigenetics, chromatin reconstitution, and nucleosome-binding studies.

Product Name

Recombinant Human Histone H1.2 Protein

SKU

rp365703

Protein Family

Linker histone H1 family (H1.2 subtype, encoded by HIST1H1C)

Biological Role

Stabilises nucleosome arrays and promotes chromatin condensation; involved in transcriptional regulation and DNA damage response

Primary Applications

Chromatin reconstitution, nucleosome-binding assays, EMSA, protein interaction studies, biochemical activity assays

Recommended Storage

Store at -80 °C; avoid repeated freeze-thaw cycles

Biological Background and Significance of Histone H1.2

Histone H1 proteins are linker histones that bind to the nucleosome core particle and the linker DNA between nucleosomes. Unlike the core histones (H2A, H2B, H3, and H4), linker histones are not integral components of the nucleosome octamer; instead, they associate with nucleosomal DNA entry and exit points to stabilise higher-order chromatin structures, facilitating the compaction of chromatin fibre into the 30 nm fibre and beyond.

In humans, the H1 family comprises multiple somatic subtypes (H1.1–H1.5), a replacement variant (H1.0), and germ-line-specific forms. H1.2, encoded by the HIST1H1C gene on chromosome 6, is one of the most abundantly expressed somatic subtypes and is present in the majority of somatic cell types. It contains three structural domains: a short, unstructured N-terminal tail; a central globular domain (GD) that contacts the nucleosome; and a long, lysine-rich C-terminal domain (CTD) responsible for DNA condensation and post-translational modification.

H1.2 plays context-dependent roles in transcriptional regulation—acting as a general repressor of transcription by limiting access of transcription factors to promoters, while also participating in specific gene activation programmes under certain conditions. Beyond transcription, H1.2 has been implicated in the DNA damage response, apoptosis signalling, and maintenance of genome stability, making it a protein of broad interest to researchers in epigenetics, cancer biology, and cell biology.

Protein Characterisation and Quality Attributes

Recombinant Human Histone H1.2 Protein (SKU: rp365703) is produced heterologously, typically in a bacterial expression system, to yield a protein that faithfully represents the human H1.2 sequence. Recombinant production enables the generation of large, consistent batches free from contaminating chromatin-associated proteins that can confound results when histones are isolated from native sources.

Key quality attributes researchers and procurement teams should verify before use include:

• Purity: High-purity preparations (typically ≥90% by SDS-PAGE) are required for biochemical and binding assays to ensure that observed activities are attributable to H1.2 and not to co-purifying contaminants. Lot-specific purity data should be reviewed on the Certificate of Analysis (CoA).
• Identity confirmation: Mass spectrometry or Western blot with an anti-H1.2 antibody confirms protein identity and distinguishes H1.2 from other H1 subtypes, which share high sequence similarity.
• Endotoxin level: For cell-based assays, low endotoxin content is critical. Confirm endotoxin specifications on the CoA if the protein will be added to mammalian cell cultures.
• Formulation: The protein is typically supplied in an aqueous buffer with stabilising additives (e.g., glycerol). Glycerol-containing buffers help maintain solubility and activity on storage but should be accounted for when setting up sensitive binding assays.

Contact Aladdin Scientific technical support to obtain the current lot CoA for rp365703 prior to experimental use.

Experimental Applications and Protocols

Recombinant Human Histone H1.2 Protein is validated for use in multiple research applications. The following guidance reflects common experimental paradigms:

Chromatin Reconstitution

H1.2 is incorporated into in vitro chromatin reconstitution experiments after assembly of core nucleosome arrays. Core histone octamers are first assembled onto DNA templates by salt-gradient dialysis or histone chaperone-assisted methods. H1.2 is then added at defined molar ratios (typically one molecule per nucleosome) to generate compacted chromatin fibre templates suitable for transcription, replication, or repair assays. The precise stoichiometry of H1.2 to nucleosomes should be optimised empirically for each experimental system.

Nucleosome-Binding and EMSA

H1.2 binds both naked DNA and nucleosome particles. Electrophoretic mobility shift assay (EMSA) can be used to characterise the binding affinity and specificity of H1.2 for different DNA or nucleosome substrates. Fluorescently labelled or radioactively labelled DNA substrates are incubated with increasing concentrations of recombinant H1.2, and complexes are resolved on non-denaturing polyacrylamide gels.

Protein–Protein Interaction Studies

Recombinant H1.2 serves as bait or prey in pull-down assays and co-immunoprecipitation experiments to identify interaction partners within the chromatin regulatory machinery, including chromatin remodelling complexes, histone chaperones, and transcription factors. GST- or His-tagged versions of H1.2 facilitate affinity-based pull-downs.

Antibody Validation and Western Blot Controls

Purified recombinant H1.2 provides a defined positive control for Western blot experiments and for validating the specificity of anti-H1.2 antibodies, particularly important given the high homology among H1 subtypes.

Storage, Handling, and Stability Recommendations

Proper handling of Recombinant Human Histone H1.2 Protein is critical to maintaining its biological activity and experimental reproducibility. Follow the guidelines below:

• Long-term storage: Store at -80 °C. Under recommended conditions, the protein retains activity for an extended period. Verify expiry or recommended use-by date on the product label and CoA.
• Avoid freeze-thaw cycling: Repeated freeze-thaw cycles lead to protein aggregation and loss of activity. Upon first thaw, prepare single-use aliquots in low-protein-binding microtubes before returning the stock to -80 °C storage.
• Working solution preparation: Thaw aliquots on ice. Gently mix by pipetting; do not vortex. Centrifuge briefly (e.g., 10 000 × g, 1 min, 4 °C) to pellet any aggregates before use.
• Protein adsorption: Histone H1.2 is a highly basic protein (high pI) and can adsorb non-specifically to standard polypropylene tubes at low concentrations. Use low-binding tubes and consider adding carrier protein (e.g., 0.1% BSA) to dilution buffers if working below 50 µg/mL, unless BSA would interfere with the assay.
• Buffer compatibility: H1.2 is stable in physiological ionic-strength buffers. Avoid prolonged exposure to extreme pH or high concentrations of reducing agents, which may compromise protein integrity.

Regulatory, Safety, and Ordering Information

Research Use Only (RUO): Recombinant Human Histone H1.2 Protein (rp365703) is intended for research use only and is not approved for diagnostic or therapeutic applications in humans or animals.

Safety: The protein is non-hazardous under standard laboratory handling conditions. Follow institutional biosafety guidelines for handling recombinant proteins. Wear appropriate personal protective equipment (gloves, lab coat, eye protection) during handling. Refer to the Safety Data Sheet (SDS) for complete hazard information.

Ordering: To order Recombinant Human Histone H1.2 Protein, reference SKU rp365703 on the Aladdin Scientific website or contact your regional Aladdin Scientific representative. Bulk quantities and custom formulations may be available on request.

Technical Support: For application-specific technical questions, CoA requests, or custom project enquiries, contact Aladdin Scientific technical support through the website or by email.

Frequently asked questions

What distinguishes Histone H1.2 from other H1 subtypes such as H1.1, H1.3, H1.4, and H1.5?

The somatic H1 subtypes share the same three-domain architecture but differ in their amino-acid sequences, particularly in the C-terminal domain, which influences their binding affinity for nucleosomes and their post-translational modification profiles. H1.2 is one of the most abundantly expressed subtypes in somatic cells and has been specifically implicated in DNA damage signalling and apoptosis regulation. Because of the high sequence similarity, subtype-specific antibodies and recombinant proteins should always be used to attribute functions to H1.2 rather than the H1 family as a whole.

How should I determine the optimal concentration of Recombinant Human Histone H1.2 Protein for my chromatin binding assay?

The optimal concentration depends on the specific assay format and the affinity of H1.2 for the substrate used. As a starting point, titrate recombinant H1.2 across a range of molar ratios relative to the nucleosome or DNA substrate (e.g., 0.25:1 to 4:1 H1.2:nucleosome) and assess complex formation by EMSA or sedimentation assay. For in vitro transcription or replication assays on reconstituted chromatin, a 1:1 molar ratio of H1.2 to nucleosome is commonly used as a baseline. Empirical optimisation is essential for each experimental system.

Can Recombinant Human Histone H1.2 Protein be used directly in cell-based experiments?

Recombinant H1.2 is primarily intended for cell-free biochemical assays. Direct addition to cell culture medium is generally ineffective because intact histones do not readily cross the plasma membrane. Researchers wishing to study H1.2 function in cells typically employ plasmid-based overexpression, siRNA-mediated knockdown, or CRISPR-based gene editing strategies. If the recombinant protein is used in cell-based assays requiring addition to culture (e.g., conditioned medium studies), ensure that endotoxin levels are below the threshold that would activate innate immune responses in the cell line used.

What is the recommended way to verify the activity of a new lot of Recombinant Human Histone H1.2 Protein?

A straightforward activity verification approach is to perform a DNA-binding EMSA using a well-characterised DNA substrate alongside a reference lot of H1.2 or a positive control. Confirm that the new lot produces a characteristic electrophoretic mobility shift pattern consistent with H1.2–DNA complex formation. Additionally, review the lot-specific CoA provided by Aladdin Scientific, which should include purity (SDS-PAGE), identity (Western blot or mass spectrometry), and endotoxin data. Contact Aladdin Scientific technical support if activity falls outside expected parameters.

References

1. Laybourn, P.J. & Kadonaga, J.T. Role of nucleosomal cores and histone H1 in regulation of transcription by RNA polymerase II. Science (1991).
2. Happel, N. & Doenecke, D. Histone H1 and its isoforms: contribution to chromatin structure and function. Gene (2009).
3. Izzo, A. et al. The genomic landscape of the somatic linker histone subtypes H1.1 to H1.5 in human cells. Cell Reports (2013).
4. Talasz, H. et al. Site-specifically phosphorylated forms of histone H1.2 and H1.4 are selectively triggered by agents mediating distinct pathways of cell death in synchronised cells. Journal of Biological Chemistry (2002).

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.