A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Purification, quaternary structure and immunological properties of phosphorylase kinase from chicken skeletal muscle

Phosphorylase kinase was isolated from red and white chicken skeletal muscle in a nearly homogeneous state as judged by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The molecular weight of the native enzyme as determined by gel filtration on Sepharose 4B is close to that of rabbit skeletal muscle phosphorylase kinase (i. e., approximately 1300 000). The molecular weights of the subunits determined by SDS gel electrophoresis are: alpha', 140 000 beta, 129 000; gamma', 44 000; delta, 17 000 (cf. the Mr values of the alpha- and gamma-subunits of the rabbit muscle isoenzyme are 146 000 and 42 000). The four subunits, alpha', beta, gamma' and delta, were found to exist in equimolar amounts as shown by a densitometric analysis of acrylamide gels; hence, the subunit formula of the chicken skeletal muscle isoenzyme is (alpha' beta gamma' delta)4. Rabbit antisera against a mixture of alpha'- and beta-subunits of chicken phosphorylase kinase yield a single precipitin line with this enzyme, do not show cross reactions of identity with the rabbit muscle enzyme but strongly inhibit the activity of the chicken enzyme and partially inhibit the activity of the rabbit muscle isoenzyme.     

Role of formic acid in transformation of acetic and succinic acids in animal tissues

Acetic and succinate acids KoA acyl derivatives interacting with formate were displayed to produce alpha-ketoacids--pyruvate and alpha-ketoglutarate. These acids also interact with formate and make pyruvic and malate acids, while alpha-ketoglutarate, evidently, tricarboxy acids. Interaction of formate with acetic and succinate acids inspite of occurring out of the tricarbone cycle increases the latter metabolic functions.     

Various metabolic reactions of formate in animal tissues

A new metabolic reaction of the aldolase condensation between formic acid and acetaldehyde proceeding with the formation of milk acid is detected in the liver of rats. Milk acid has been determined by chemical, enzymic and autoradiographic methods. Homogeneous preparations of the enzyme which catalyzes the mentioned reactions and is called lactate synthase are obtained in the crystalline form. The method for obtaining the lactate synthase from the rat liver is described as well as certain properties of the lactate synthase.     

Influence of formate on free amino acids contents in tissues and organs of rats in vitro and in vivo

In experiments in vitro and in vivo influence of formiate on free amino acids contents of tissues and organs of rats has been studied. Results of experiments showed a possibility of amino acids formilation in all investigated tissues. This process could be enzymatic. Its effectivness depended on amino acids and formiate concentrations. The most effective processes took place in organs with high metabolic activity.     

Possibility of enzymatic lactate disintegration followed by formate production

A possibility of lactate reverse desintegration to formate and acetaldehyde by lactate-synthase was established by the methods of enzymatic analysis, isotope indication, thin layer chromatography.     

Limited proteolysis and phosphorylation of phosphorylase kinase from chicken skeletal muscles

The changes in the quaternary structure of chicken skeletal muscle phosphorylase kinase during limited proteolysis by trypsin and chymotrypsin were studied. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate of the products of phosphorylase kinase limited proteolysis revealed a similarity in the structure of the alpha'- and beta-subunits and some differences in the structure of the gamma-subunits of the chicken and rabbit enzymes. Phosphorylation with the catalytic subunit of cAMP-dependent protein kinase (up to 2 mol of 32P/mol of alpha' beta gamma' sigma monomer) and autophosphorylation (up to 8 mol of 32P/mol alpha' beta gamma' delta monomer) increased the activity of chicken phosphorylase kinase 1.5-fold and 2.0-fold, respectively. The incorporation of phosphate into the alpha' and beta-subunits in the course of the protein kinase-catalyzed reaction was demonstrated.