Recently, a specific peptide inhibitor for ATGL was isolated from white blood cells, specifically mononuclear cells. This peptide was originally identifed as being involved in the regulation of the G 0 to G 1 transition of the cell cycle . This peptide was, therefore, called G0G1 switch protein 2 (G0S2). The protein is found in numerous tissues, with highest concentrations in adipose tissue and liver. In adipose tissue G0S2 expression is very low during fasting but increases after feeding. Conversely, fasting or PPARα-agonists increase hepatic G0S2 expression. The protein has been shown to localize to LDs, cytoplasm, ER, and mitochondria. These different subcellular localizations likely relate to multiple functions for G0S2 in regulating lipolysis, the cell cycle , and, possibly, apoptosis via its ability to interact with the mitochondrial antiapoptotic factor Bcl-2. With respect to ATGL regulation, the binding of the enzyme to LDs and subsequent is dependent on a physical interaction between the N-terminal region of G0S2 and the patatin domain of ATGL.
Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  :10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity.