Insulin is a peptide hormone produced by beta (β) cells of the pancreatic islets considered to be the main anabolic hormone of the body. Insulin is synthesized as a single-chain precursor, preproinsulin, that contains an N-terminal signal sequence and a connecting peptide (C-peptide) linking the A and B chains of the insulin molecule (proinsulin) (Steiner, Cunningham et al. 1967, Dodson and Steiner 1998). Within the endoplasmic reticulum of the β cell, proinsulin is exposed to several specific endopeptidases which excise the C peptide, thereby generating the mature form of insulin; insulin and free C peptide are packaged in the Golgi into secretory granules which accumulate in the cytoplasm for release when systemic glucose level increase. Insulin is not only a biomarker used in the identification of pathologies associated with glucose metabolism such as Type 1 and Type 2 diabetes; the secretion of insulin rises with age, which is related to both increasing body fat mass and ageing itself (Thorens, Rodriguez et al. 2019). Similarly, levels of circulating C peptide are being considered as potential biomarkers for certain cancers and atherosclerotic disease (Murphy, Cross et al. 2015, Cardellini, Farcomeni et al. 2017, Khan, Sobki et al. 2018). Figure 1 demonstrates that while the A and B chains of HUM and RHE insulin have the same sequences, MAR insulin has significant aminoacid differences with HUM insulin. We found one Luminex kit (Biorad) that had reactivity with MAR samples, but no reagents able to recognize MAR C peptide.



Protein alignment for human, rhesus macaque and marmoset insulin:

image of Protein alignment for human, rhesus macaque and marmoset Insulin


Protein alignment for marmoset, owl monkey, and squirrel monkey insulin:

Protein alignment for marmoset, owl monkey, and squirrel monkey insulin



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Mice have been immunized with recombinant marmoset protein.