Summary: | The Amyloid Precursor Protein (APP) is a causative agent in Alzheimer’s disease (AD) as the Aβ fragment of this protein builds up in brain lesions of AD patients and mutations in APP lead to heritable forms of the disorder. APP contains a single transmembrane domain and a highly conserved region at the tip of the C‐terminus. Here, we show that APP associates with isolated axoplasmic organelles purified from the axoplasm of the squid giant axon. We have also identified the coding sequence of squid APP from a cDNA library of the North Atlantic Long‐finned Squid, Loligo pealei. We have cloned the full‐length coding sequence and are currently over‐expressing and purifying recombinant squid APP to establish a standard curve for quantitative Western blot to determine the concentration of APP in whole axoplasm and in isolated organelle fractions. Squid provide the only source of pure axoplasm as this organism contains a large axon up to 1 mm in diameter, allowing for the extrusion of cytoplasm away from the cell body, cell membrane, and other types of neuronal tissues. Quantifying the amount of APP in axoplasm and the number of APP molecules per organelle may provide insight into the wild‐type function of APP. Grant Funding Source : Supported by the Rhode Island INBRE Program NIMGS grant 5 P20 GM103430‐13
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