Parathyroid hormone (1-34) (human): Precision Tool for Calcium Homeostasis and Bone Metabolism Research

Executive Summary: Parathyroid hormone (1-34) (human) is a synthetic peptide corresponding to the biologically active N-terminal 34 amino acids of human parathyroid hormone, with a molecular weight of 4117.72 Da and sequence H2N-SVSEIQLMHNLGKHLNSMERVEWLRKKLQDVHNF-OH. It acts as a high-affinity agonist for both PTH1R and PTH2R, exhibiting an IC₅₀ of 0.22 nM for cAMP stimulation in human kidney 293 cells (APExBIO, A1129). The peptide robustly regulates serum calcium, enhances bone mass in vivo, and is highly soluble in DMSO (≥399.3 mg/mL) and water (≥19.88 mg/mL), but is insoluble in ethanol. Supplied at >97.8% purity, it is essential for bone metabolism, osteoporosis modeling, and advanced PTH/PTHrP receptor signaling research (Huang et al., 2025).

Biological Rationale

Parathyroid hormone (1-34) (human), a synthetic analog of the endogenous hormone, is derived from the first 34 amino acids secreted by chief cells of the human parathyroid glands. This fragment retains full biological activity for PTH1R and PTH2R signaling, as found in native hormone-mediated calcium regulation (APExBIO). Its primary physiological role is to maintain serum calcium concentrations within a narrow range, facilitating neuromuscular function, blood coagulation, and bone remodeling processes. In translational research, this peptide is pivotal for dissecting the mechanisms of calcium homeostasis, bone formation, and mineral metabolism (Related: Amyloid.co (2023)). This article extends mechanistic clarity on intracellular signaling beyond prior reviews.

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

PTH (1-34) binds to two G protein-coupled receptors: PTH1R, predominantly in bone and kidney, and PTH2R, with more restricted tissue distribution. Upon ligand binding, PTH1R activates multiple intracellular signaling pathways, primarily:

• cAMP Pathway: Activation of adenylate cyclase leads to rapid elevation of intracellular cAMP, with a half-maximal effective concentration (IC₅₀) of 0.22 nM in human kidney 293 cells (APExBIO).
• Inositol Phosphate Pathway: Stimulation of phospholipase C increases inositol phosphate synthesis, triggering calcium release from intracellular stores (Huang et al., 2025).
• Downstream Effects: These cascades result in increased calcium mobilization from bone, enhanced reabsorption of calcium and magnesium in the kidney distal tubules and thick ascending limb, and augmented intestinal calcium absorption via upregulation of 1,25-dihydroxyvitamin D production.

These mechanisms underpin its use as a robust parathyroid hormone 1 receptor agonist and calcium homeostasis regulator in both in vitro and in vivo models (Related: Vitamin D-binding Protein Precursor (2023)). This extension focuses on cAMP and inositol phosphate signaling kinetics in human kidney assembloid systems.

Evidence & Benchmarks

• PTH (1-34) (human) stimulates cAMP production with an IC₅₀ of 0.22 nM in transfected human kidney 293 cells (APExBIO).
• Subcutaneous administration of 10 or 40 μg/kg/day in male Fisher 344 rats increases both trabecular and cortical bone mass in a dose- and time-dependent manner (Huang et al., 2025).
• The peptide is soluble at ≥399.3 mg/mL in DMSO and ≥19.88 mg/mL in water, but insoluble in ethanol, facilitating versatile experimental formulations (APExBIO).
• In kidney assembloid models, PTH (1-34) enables precise recapitulation of nephron signaling and calcium regulatory functions, improving model fidelity for late-onset kidney diseases (Huang et al., 2025).
• The product is supplied at >97.8% purity, ensuring reproducibility in sensitive cell viability and signaling assays (Parathyroid-hormone1-34.com (2023)).

Applications, Limits & Misconceptions

Parathyroid hormone (1-34) (human) is extensively used for:

• Modeling bone metabolism and osteoporosis in rodents and organoid systems.
• Studying calcium and magnesium handling in kidney, including advanced assembloid models.
• Dissecting cAMP and inositol phosphate signaling in PTH/PTHrP receptor research.
• Optimizing cell viability, proliferation, and cytotoxicity assays due to predictable signaling kinetics.

This article clarifies the peptide's mechanistic boundaries in kidney and bone models, extending prior reviews (Related: Vitamin D-binding Protein Precursor (2023)).

Common Pitfalls or Misconceptions

• Not a full-length hormone: PTH (1-34) does not recapitulate all biological activities of the 84-amino acid native hormone, especially in non-classical tissues.
• Not for clinical or diagnostic use: This reagent is for research use only; it is not validated for therapeutic or medical diagnostics (APExBIO).
• Solubility limitations: The peptide is insoluble in ethanol and can aggregate if not properly dissolved in DMSO or water at recommended concentrations.
• Storage stability: Long-term storage of solutions at room temperature can lead to degradation; only freshly prepared aliquots should be used for experiments.
• Species specificity: While functional in rodent and human systems, cross-species activity may not be identical; always validate in the target model.

Workflow Integration & Parameters

• Formulation: Prepare stock solutions in DMSO (≥399.3 mg/mL) or water (≥19.88 mg/mL) under sterile, desiccated conditions at -20°C.
• Dosing: In vivo studies use subcutaneous doses ranging from 10 to 40 μg/kg/day, with documented increases in bone mass within 4–8 weeks in Fisher 344 rat models (Huang et al., 2025).
• Assay compatibility: Suitable for cell viability, cAMP, inositol phosphate, and mineralization assays in human and rodent cells (Parathyroid-hormone1-34.com (2023)).
• Quality control: Supplied at >97.8% purity; batch validation includes HPLC and mass spectrometry.
• Product information: For detailed protocols and batch-specific data, consult the Parathyroid hormone (1-34) (human) A1129 kit page from APExBIO.

Conclusion & Outlook

Parathyroid hormone (1-34) (human) is a validated research tool for dissecting calcium homeostasis and bone remodeling mechanisms. Its high specificity for PTH1R, robust signaling induction, and well-characterized solubility and storage parameters make it essential for advanced kidney and bone disease modeling. Recent advances in kidney assembloid technologies further highlight its translational relevance (Huang et al., 2025). Ongoing improvements in organoid maturity and model fidelity will expand its applications in regenerative medicine and precision pharmacology.