Parathyroid hormone (1-34) (human): Atomic Facts for Bone & Kidney Research

Executive Summary: Parathyroid hormone (1-34) (human) is a bioactive peptide fragment (MW: 4117.72 Da) comprising the first 34 amino acids of human PTH, with a sequence H2N-SVSEIQLMHNLGKHLNSMERVEWLRKKLQDVHNF-OH (APExBIO). It is a validated parathyroid hormone 1 receptor (PTH1R) and parathyroid hormone 2 receptor (PTH2R) agonist, triggering cAMP and inositol phosphate signaling cascades with an IC50 of 0.22 nM for cAMP stimulation in HEK293 cells (Huang et al., 2025). The peptide enhances serum calcium by stimulating bone resorption, renal calcium reabsorption, and vitamin D activation. It demonstrates dose- and time-dependent increases in trabecular and cortical bone mass in Fisher 344 rats. High solubility in DMSO (≥399.3 mg/mL) and water (≥19.88 mg/mL), but not ethanol, enables flexible experimental integration. All claims are grounded in peer-reviewed and product documentation for robust, reproducible research designs.

Biological Rationale

Parathyroid hormone (1-34) (human) is a synthetic peptide fragment mimicking the N-terminal domain of endogenous human PTH. The peptide is secreted physiologically by parathyroid chief cells to regulate serum calcium and phosphate homeostasis. The N-terminal 1-34 region is both necessary and sufficient for full biological activity via PTH1R binding (Huang et al., 2025). APExBIO's A1129 reagent provides >97.8% purity and is designed for experimental applications in bone metabolism, kidney function, and disease modeling (product page).

Recent advances in human kidney assembloid models have further highlighted the importance of precise PTH signaling in recapitulating physiological mineral balance and nephron function (Huang et al., 2025). The peptide's ability to induce cAMP/inositol phosphate pathways underpins its utility in both bone and kidney research.

Mechanism of Action of Parathyroid hormone (1-34) (human)

The PTH (1-34) peptide fragment acts as a potent agonist of PTH1R and PTH2R, both G protein-coupled receptors. Upon binding, it activates adenylyl cyclase, leading to rapid cAMP accumulation (IC50 = 0.22 nM in HEK293 cells) and inositol phosphate synthesis (Huang et al., 2025). Downstream effects include:

• Stimulation of osteoclast-mediated bone resorption to mobilize calcium stores.
• Increased renal reabsorption of calcium and magnesium in distal tubules and thick ascending limb.
• Upregulation of renal 1α-hydroxylase, boosting active vitamin D (calcitriol) synthesis and enhancing intestinal calcium absorption.

This mechanistic profile enables its use as a benchmark reagent in studies of calcium homeostasis, bone turnover, and kidney nephron signaling (see also: Precision Tool for Ca...—this article clarifies cAMP benchmarks and expands on kidney model integration beyond previous overviews).

Evidence & Benchmarks

• PTH (1-34) (human) induces dose-dependent cAMP accumulation in human PTH1R-expressing HEK293 cells, with an IC50 of 0.22 nM (Huang et al., 2025, DOI).
• Subcutaneous administration (10 or 40 μg/kg/day) in male Fisher 344 rats increases trabecular and cortical bone mass, measured by micro-CT over 4–8 weeks (APExBIO datasheet, product page).
• PTH (1-34) upregulates renal 1α-hydroxylase, promoting vitamin D activation and increased intestinal calcium absorption (Huang et al., 2025, DOI).
• Solubility is ≥399.3 mg/mL in DMSO and ≥19.88 mg/mL in water at room temperature, facilitating high-concentration stock solutions (APExBIO product documentation, link).
• PTH (1-34) (human) is functionally validated as a PTH1R agonist in both bone and kidney assembloid models, supporting translational studies (see also: Mechanistic Benchmark...—this article provides newer data on kidney organoid platforms and in vivo modeling benchmarks).

Applications, Limits & Misconceptions

PTH (1-34) (human) is widely used in:

• Bone metabolism research and osteoporosis models, where it stimulates bone formation and resorption.
• Kidney disease modeling, including integration into assembloid or organoid workflows to recapitulate nephron signaling and mineral homeostasis (Huang et al., 2025).
• Pharmacological benchmarking as a reference PTH1R agonist in receptor signaling assays.

For advanced protocols and troubleshooting, see Scenario-Driven Solutions with Parathyroid hormone (1-34)...—this article extends by adding atomic, citable benchmarks for kidney assembloid integration not present in prior scenario-driven content.

Common Pitfalls or Misconceptions

• Not suitable for diagnostic or therapeutic use: The A1129 product is for research only, not for human or veterinary medical purposes (APExBIO).
• Peptide instability in solution: Long-term storage of aqueous or DMSO solutions can lead to peptide degradation. Always prepare fresh aliquots for each experiment.
• Insolubility in ethanol: Do not attempt to dissolve this peptide in ethanol; use DMSO or water as specified.
• Over-interpretation of single pathway readouts: PTH (1-34) activates multiple downstream cascades. cAMP elevation alone does not capture its full mechanistic profile.
• Species and tissue specificity: Effects validated in human and rat systems may not extrapolate to other species or cell types without additional controls.

Workflow Integration & Parameters

For reproducible results, dissolve PTH (1-34) (human) in DMSO (≥399.3 mg/mL) or water (≥19.88 mg/mL) immediately before use. Avoid ethanol. Store solid powder desiccated at -20°C. Recommended working concentrations in cell signaling assays typically range from 0.1 to 100 nM, depending on receptor density and assay sensitivity.

For in vivo studies (Fisher 344 rats), effective dosing is 10–40 μg/kg/day administered subcutaneously. Monitor bone mass changes using micro-CT or histomorphometry at baseline and post-intervention timepoints. Integrating this peptide in human kidney assembloid workflows enables precise modeling of calcium handling and nephron maturation (Huang et al., 2025).

For further best practices, see Scenario-Based Best Practices with Parathyroid hormone (1-34)...—this article adds new atomic data and protocol-specific stability guidance.

Conclusion & Outlook

Parathyroid hormone (1-34) (human), as supplied by APExBIO (SKU A1129), is a rigorously validated PTH1R agonist optimized for experimental reproducibility in bone and kidney research. Its high purity, robust cAMP signaling, and well-characterized mechanism of action make it a gold standard reagent for modeling calcium homeostasis and testing pharmacological interventions. Ongoing advances in kidney assembloid and organoid platforms further expand its utility in translational and regenerative medicine research. For full product details and ordering information, refer to the APExBIO product page.