The Eagle Biosciences ELISA for ALS E35 is a so-called Sandwich-Assay. It utilizes two specific and high affinity antibodies for this protein. These antibodies were created by immunization of rabbits with specific peptides as previously described by Khosravi and Stadler [16, 17]. The ALS in the sample binds to the immobilized first antibody on the microtiter plate. In the following step, the biotinylated and Streptavidin-Peroxidase conjugated second specific anti-ALS-Antibody binds in turn to the immobilized ALS. In the closing substrate reaction the turn of the colour will be high specific catalysed, quantitatively depending on the ALS-level of the samples. Sample Types: serum, plasma. Range: 1.5 - 40 mU/ml. Sensitivity: 0.2 mU/ml. Time: 3 hours ? The acid-labile Subunit, is a synthezised as propeptide of 605 amino acids. The signal peptide, necessary for ALS secretion (AA 1-27) cleaved off enduring the transport process (Swiss-Prot P35858 Version 82). The mature protein consists of 578 amino acids and contains about 20 leucin rich sequence repeats. Beside the leucin-rich repeats several potential N-linked glycosylation sides have been described. Miller BS et al. were able to demonstrate that incomplete glycolsylation of IGFs, ALS and IGFBP-3 results in a decreased serum concentration of these proteins. Oral mannose therapy resulted in a partial normalization of the glycosylation pattern and went along with improved growth [8]. Mutations in or the complete knock out of the ALS gene result in IGF / IGFBP-3 deficiency and therewith in disturbation of growth [9,10]. Beside growth also other Endocrinology axes may be involved. In primary ALS deficiency hyperinsulinemia could be observed [11, 12]. Further, the ALS-IGF-IGFBP-system seems to be of relevance in coronary disease [13].