Calcitonin receptor-targeting peptide fragment (CGRP-I precursor 96-119)
A natural fragment of a body protein that switches on the calcitonin receptor, which helps control bone turnover and metabolism; used only as a lab research tool.
- Class
- Endogenous peptide fragment (human)
- Status
- No approved therapeutic status identified
- Best-supported effect
- Peptidomic identification as a candidate neuroendocrine regulatory peptide; no validated bioactivity attached to this card
- Main caveat
- Card sourced from a vendor catalog entry and a single peptidomic identification study. No functional assays, animal studies, or human trials are attached.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
This peptide is a 24-residue fragment spanning positions 96 to 119 of the calcitonin gene-related peptide I (CGRP-I) precursor protein — one of several bioactive sequences that can be released from this precursor through proteolytic processing. It is an endogenous fragment, meaning it arises from a protein the body already makes, rather than being a purely synthetic compound. Its primary target is the calcitonin receptor (CALCR), a class B secretin-family G protein-coupled receptor that is central to bone resorption signaling and is shared — in different receptor complexes — by calcitonin, amylin, and related peptides (Hay and colleagues 2018). The fragment's relevance has grown alongside interest in amylin receptor pharmacology, particularly as a tool for probing the receptor system that cagrilintide and similar dual-agonist drugs engage.
What it does
The calcitonin receptor that this fragment targets is expressed on osteoclasts (bone-resorbing cells), kidney tubule cells, and neurons, where its activation suppresses bone resorption and modulates calcium handling (Pondel 2000). CALCR can form functional complexes with receptor activity-modifying proteins (RAMPs), and the resulting heterodimers define the AMY₁, AMY₂, and AMY₃ amylin receptor subtypes — distinct pharmacological entities from the plain calcitonin receptor (Hay and colleagues 2018; Barwell and colleagues 2012). This fragment from the CGRP-I precursor is used in research to probe which receptor configurations a test compound engages and with what affinity. Its utility is characterizing the signaling landscape shared by calcitonin, amylin, and CGRP family peptides rather than serving as a therapeutic compound in its own right.
Evidence
- Human: No human clinical data for this specific fragment. It is a research tool peptide.
- Animal: Used in receptor pharmacology studies as a probe for CALCR and CALCR/RAMP complex activity.
- In vitro: Characterization of this and related CGRP-I precursor-derived fragments has been supported by peptidomic identification methods (Yamaguchi and colleagues 2007). CALCR expression during osteoclast differentiation — relevant to assessing this fragment's functional context — has been documented in mouse bone marrow macrophage models (Granholm and colleagues 2008).
Mechanism
CALCR is a class B (secretin-family) GPCR that couples primarily through Gαs to activate cAMP signaling, and through Gαq to mobilize intracellular calcium, depending on cell type (Barwell and colleagues 2012). When CALCR associates with RAMP1, RAMP2, or RAMP3, it generates the AMY₁, AMY₂, and AMY₃ receptor subtypes respectively — pharmacological configurations with distinct ligand-selectivity profiles for amylin versus calcitonin (Hay and colleagues 2018). The CGRP-I precursor fragment [96-119] falls outside the mature CGRP sequence itself (which occupies different residue positions in the precursor) and represents a region of the precursor whose bioactive status was explored through peptidomic approaches (Yamaguchi and colleagues 2007). In the context of modern weight-management pharmacology, CALCR and the AMY receptor subtypes it forms are directly engaged by cagrilintide, the amylin analog component of the CagriSema combination; this fragment's receptor targets are therefore the same system that dual GLP-1R/amylin receptor agonists modulate.
Related peptides
- α-CGRP (CGRP-I) — the mature bioactive peptide derived from the same CGRP-I precursor; acts at CLR/RAMP1 rather than CALCR
- Calcitonin — the canonical CALCR agonist, inhibits osteoclast-mediated bone resorption; shares the receptor this fragment targets
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.762283444404602 | boltz-2 |
| ranking score | 0.6247828602790833 | boltz-2 |
▸3-letter notation
▸recipeboltz-2 2.2.1
| parameter | value |
|---|---|
| model | boltz-2 2.2.1 |
| weights | — |
| hardware | vast_v100_32gb |
| mlx version | — |
| python | — |
| random seed | 1 |
| msa strategy | colabfold_local |
| runtime | — |
| predicted by | — |
| predicted at | 2026-05-22 |
▸citationbibtex
@peptide{pep10552,
sequence = {GLLSRSGGVVKNNFVPTNVGSKAF},
target = {calcr},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}