Isolation of two 67 kDa calcium‐binding proteins from pig lung differing in affinity for phospholipids and in anti‐phospholipase A₂ activity

Abstract

Two 67 kDa proteins adsorbed to membranes in the presence of Ca 2t have been purified to homogeneity from pig lung using conventional procedures, followed by calcium-dependent affinity chromatography on polyacrylamide-immobilized phosphatidylserine. The two proteins were, respectively, excluded (67E) and retained (67R) on the column in the presence of Ca 2f . On the basis of amino acid composition and isoelectric point, 67R was identified as 67 kDa calelectrin/calcimedin, whereas 67E could be differentiated from albumin, calregulin, 67 kDa fragment of protein kinase C and surfactant-associated proteins. Only 67R was slightly phosphorylated by protein kinase C, reacted with an antibody raised against 32.5 kDa endonexin and inhibited pig pancreas phospholipase Al in a way similar to that of lipocortin or endonexin. These data bring further support to the view that inhibition of phospholipase AZ by lipocortin or other related proteins involves interaction with the lipid/water interface. They also provide evidence for a new kind of Ca2+-binding protein (67E), whose role still remains to be determined.Ca2+-binding protein; Lipocortin; Phospholipase AZ; Phosphatidylserine; (Lung)

Role of phospholipase A2 in the stimulation of sponge cell proliferation by homologous lectin

“…Interestingly, the extracellular compartment of the sponge also contains the inhibitor of phospholipase API calelectrin (Fauvel et al, 1987). We found that this protein is associated with the sponge AF particle and noncompetitively inhibits the homologous enzyme.…”

“…In view of an earlier finding that phospholipase A2 activity is inhibited by calelectrin (Fauvel et al, 1987), we preincubated both the cell extract and the extracellular material with antibodies against calelectrin prior to the determination of enzyme activity. After this treatment, the activity increased 3.4-fold in the extracellular material, but only 1.15fold in the cellular extract (Table 1).…”

Annexins in cardiac tissue: cellular localization and effect on phospholipase activity

“…Beside anticoagulant activity, Annexin Vr and Annexin VIIIr were found to inhibit the activity of soluble pancreatic phospholipase A2, when (3H)-oleic acid labeled E. coli membranes are used as substrate [10]. Using comparable in vitro systems other members of the annexin family were found to inhibit the activity of soluble or solubilized phospholipases [18][19][20]. In the isolated lung human recombinant lipocortin I (Annexin I) was able to suppress thromboxane synthesis, when added to the perfusion medium [21].…”

“…This model has been found useful for studies employing soluble or solubilized phospholipases. As stated above, conclusions concerning the phospholipase inhibitory effect and mechanism of action of annexins are primarily based on studies using soluble pancreatic phospholipase A2 as model enzyme and artificial membranes as substrate [10,[18][19][20]. The availability of large amounts of recombinant Annexin V enabled us to study the effect of annexins on PL hydrolysis in a more natural setting, i.e.…”

Influence of fibroblast growth factor on phosphorylation and activity of a 34 kDa lipocortin‐like protein in bovine epithelial lens cells

“…Basic FGF was purified from bovine brain as in [11,12]. Lipocortin from pig lung was prepared as in [13] and kindly provided by Drs Josette Fauvel and Hugues Chap 0d 101 INSERM, Toulouse).…”