Zinc α2-Glycoprotein: A Multidisciplinary Protein

Abstract

Zinc A2-glycoprotein (ZAG) is a protein of interest because of its ability to play many important functions in the human body, including fertilization and lipid mobilization. After the discovery of this molecule, during the last 5 decades, various studies have been documented on its structure and functions, but still, it is considered as a protein with an unknown function. Its expression is regulated by glucocorticoids. Due to its high sequence homology with lipid-mobilizing factor and high expression in cancer cachexia, it is considered as a novel adipokine. On the other hand, structural organization and fold is similar to MHC class I antigen-presenting molecule; hence, ZAG may have a role in the expression of the immune response. The function of ZAG under physiologic and cancerous conditions remains mysterious but is considered as a tumor biomarker for various carcinomas. There are several unrelated functions that are attributed to ZAG, such as RNase activity, regulation of melanin production, hindering tumor proliferation, and transport of nephritic by-products. This article deals with the discussion of the major aspects of ZAG from its gene structure to function and metabolism. (Mol Cancer Res 2008;6(6):892 -906)

The detection and measurement of interleukin-6 in venous and capillary blood samples, and in sweat collected at rest and during exercise

“…However, in agreement with Raiszadeh et al, the present data do not support the notion that IL-6 is present in sweat in detectable levels and we suggest that measurement of IL-6 in sweat is not a valid or reliable measurement of systemic IL-6. Moreover, of 180 proteins identified in sweat, only albumin, zinc α2 glycoprotein, gelsolin, apolipoprotein D and clusterin 1 were present in both sweat and plasma (Raiszadeh et al 2012), indicating that future work aimed at using sweat as a potential vehicle for biomarkers or disease should focus on these proteins, as they have already been linked to a number of diseases and pathological conditions (Ceperuelo-Mallafré et al 2009;Dubois et al 2010;Hassan et al 2008;Mracek et al 2011;Rydén et al 2012;Yang et al 2013). …”

Changes in the salivary protein profile of morbidly obese women either previously subjected to bariatric surgery or not

“…The exact effect of these proteins in taste perception is not known. Whereas zinc-alpha-2 glycoprotein is a protein with different functions, among which is initiation of lipid mobilisation [18], cystatins are cysteine protease inhibitors. These last are involved in the control of proteolysis within the oral cavity, and, for that reason, it was hypothesised that they could affect the accessibility of tastant molecules to taste receptors, influencing taste sensitivity [15].…”

Tear proteomics in evaporative dry eye disease

“…30 The exact function of ZAG in tears and its possible role in lipid degradation have only been postulated and not completely clarified. 31,32 In our study, we detected ZAG in both patients and controls, with no statistically significant differences in the respective expression.…”