Adipose tissue is the largest reservoir of fuel, storing energy in the form of rapidly utilizable triglycerides. Adipocytes synthesize and store energy in periods of nutritional abundance and mobilize lipids during starvation and other times of need. The switch from energy storage to expenditure is finely regulated by a variety of hormones. In order to accomplish these complex tasks energy balance, adipocytes express many genes involved in lipid metabolism and glucose homeostasis. Some of the these genes include fatty acid synthase, fatty acid binding protein aP2, lipoprotein lipase, phosphoenolpyruvate carboxy kinase, malic enzymes, glyceralduhyde-3-phosphate dehydrogenase, glut-4, IGF-1, insulin receptors, TNF-a, the product of obese gene leptin, resistins, Adipsin, Acrp30, Uncoupling proteins (UCPs), PPARs, pref-1, among others. Many of these genes are finely regulated during adipocyte differentiation and maturation. Several adipocyte-derived proteins act in an autocrine or paracrine fashion to control its own and other cell's cellular physiology.

Adipsin is serine protease that is secreted by adipocytes. It is deficient in several animal model of obesity. Adipsin has now been identified as the same protein as complement factor D. Adipsin, also called ADN or complement factor D or C3 convertase activator or properdin factor D (precursors: mouse 259-aa; rat 263 aa, human 253 aa, mature protein 26-253, ~22 kDa) cleaves factor B when the latter is complexed with factor C3B, activating the C3BB complex, which then becomes C3 convertase of the alternative pathway. Adipocyte is the major protein secreted by the adipocytes. Unlike rodents, adipsin is also expressed in monocytes/macrphages. Most adipsin is secreted in blood (50 ug/ml in normal lean mice and 50-100 fold less in fat from db/db or ob/ob or MSG (monosodium glutamate-treated mice). Its expression is induced upon differentiation of preadipocytes.

Preadipocyte factor-1 (Pref-1), an epidermal growth factor-like domain-containing transmembrane protein is implicated in inhibiting preadipocytes differentiation. Pref-1 (mouse 385-aa, rat 383-aa, human 383-aa, chromosome 14q32), also known as fetal antigen 1 (FA1), Delta Drosophila homolog-like 1 (DLK1) or Zona glomerulosa-specific factor (ZOG), is synthesized as a membrane protein in preadipocytes but it is not detectable in mature adipocytes. Dexamethasone, a promoter of adipocyte differentiation, down regulates Pref-1. Pref-1 is proteolytically cleaved to generate a biologically active 50-kDa ectodomain (24-303 aa) or soluble form. Constitutive expression of Pref-1 or addition of its ectodomain inhibits adipogenesis. There are at least four major isoforms (45-60 kDa) of Pref-1 generated by alternatively splicing. Pref-1/DLK is expressed in tumors with neuroendocrine features, such as neuroblastoma, pheochromocytoma, and a subset of small cell lung carcinoma cell lines. Its expression in normal tissues is restricted to the adrenal gland and placenta.
   
 

M= Mouse; R=Rat; H=Human; Rb=Rabbit; Sh=Sheep; G=goat; B=Bovine, MO=Monkey; P=pig; CT= near C-terminus; NT=near N-terminus; CP=cytoplamsic domain; EC=Extracellualr domain; Internal=Middle of protein. *

** Expected antibody crossreactivity information is mostly based upon high (>70%) sequence conservation of antigenic/control peptides in various species. When antibody crossreactivity has actually been experimentally confirmed in various species, it will be mentioned in the appropriate data sheets.

"Neat Antisera or antisera" are the unpurified antiserum and it is suitable for ELISA and Western.
"Affinity pure" IgG may be more suitable for immunohistochemical (IHC) applications and to reduce background in most immunological applications including ELISA and Western.
"Control peptides" can not be used for Western as they are very short peptides. They are intended for ELISA or antibody blocking studies to establish antibody specificity.
Western blot +ve protein controls, where available, are semi-pure, pure or recombinant proteins that are formulated in SDS-PAGE sample buffer. They are recommended to be used for Western (load 10 ul/lane) for visulaization with antibodies.