IGF-DES

IGF-1 DES (Des(1-3)IGF-1), or Des(1-3) Insulin-like Growth Factor-1, is a truncated analog of IGF-1. It is a 67-amino acid polypeptide derived from the 70-amino acid sequence of IGF-1 by deleting the N-terminal tripeptide (glycine-proline-glutamate).

Structural Modification

This N-terminal deletion alters the peptide's binding characteristics relative to full-length IGF-1. In vitro studies have shown this structural change results in a significant increase in potency in assays measuring processes such as protein synthesis and cellular proliferation when compared to native IGF-1.

IGF Binding Proteins and Bioavailability

The altered properties of IGF-1 DES are related to its interaction with IGF binding proteins (IGFBPs). In circulation, most endogenous IGF-1 is sequestered by a family of six high-affinity IGFBPs, which regulate its availability to cell surface IGF-1 receptors. The N-terminal tripeptide deletion in IGF-1 DES reduces its binding affinity for IGFBPs.

This differential binding means a higher proportion of IGF-1 DES may exist in a free, unbound state capable of direct receptor engagement.

Pharmacokinetic Profile

The reduced binding to IGFBPs affects the peptide's pharmacokinetic profile. Unbound to the stabilizing IGFBP-3/ALS complex, IGF-1 DES has a reported plasma half-life of approximately 20-30 minutes in research models, compared to the much longer half-life of endogenous IGF-1. This results in rapid but transient activity in laboratory settings.

IGF-1 DES interacts with the IGF-1 receptor (IGF1R), a receptor tyrosine kinase expressed in many cell types. The IGF1R is a primary mediator of cellular growth, survival, and metabolic signaling pathways associated with IGF-1.

Receptor Structure and Activation

The IGF-1 receptor is a heterotetrameric complex with two extracellular α-subunits for ligand binding and two transmembrane β-subunits with intracellular tyrosine kinase domains. Binding of IGF-1 DES to the α-subunits induces a conformational change that triggers trans-autophosphorylation of tyrosine residues on the β-subunits.

PI3K/Akt/mTOR Signaling

Phosphorylation of the IGF1R initiates downstream signaling cascades, primarily the PI3K/Akt/mTOR pathway and the Ras/Raf/MEK/ERK MAPK cascade. In the PI3K/Akt/mTOR pathway, activated PI3K generates PIP3, which then recruits and activates the kinase Akt.

Akt phosphorylates various substrates, including mTOR, which is involved in protein synthesis, and FoxO transcription factors, which, when phosphorylated, are excluded from the nucleus, preventing the transcription of certain atrophy-related genes.

Muscle-Specific Observations

In skeletal muscle cell models, activation of these signaling pathways has been observed to be associated with an increase in muscle cell size (hypertrophy), proliferation of satellite cells, and an increase in myofibrillar protein content.

Published nonclinical literature relevant to this material's molecular targets and experimental models is listed below for independent review. Findings involving other preparations or experimental systems should not be attributed to this research material.

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Laboratory Handling

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Research Limitations

Published observations involving other preparations, experimental systems, or study populations do not establish the identity, performance, or suitability of this research material for any particular experiment.