Major Salivary Proteins Research Articles

Human salivary gustin is a potent activator of calmodulin-dependent brain phosphodiesterase.

Human salivary gustin stimulated activity of brain calmodulin-dependent cyclic nucleotide phosphodiesterase (cAMP PDEase; 3',5'-cyclic-nucleotide phosphodiesterase, EC 3.1.4.17) in a dose-dependent manner in the absence of calmodulin. At physiological levels found in human saliva, gustin activated cAMP PDEase 5- to 6-fold. Activation of PDEase occurred with as little as 500 ng of gustin. Comparative sensitivity of activation of PDEase by gustin was intermediate between calmodulin and lysophosphatidylcholine with maximal activation and half-maximal activation (indicated in parentheses) at 3 X 10(-8) M (4.3 X 10(-9) M), 3.4 X 10(-6) M (3.4 X 10(-7) M), and 2.5 X 10(-3) M (4.0 X 10(-5) M) for calmodulin, gustin, and lysophosphatidylcholine, respectively. No other major salivary protein activated PDEase. Anticalmodulin antibody completely inhibited calmodulin-activated cAMP PDEase activity, but the antibody had no effect on gustin-activated cAMP PDEase activity. A sensitive calmodulin RIA indicated that no calmodulin was detected in any gustin preparation that activated cAMP PDEase. Both gustin and calmodulin rendered cAMP PDEase thermally labile to a similar extent and increased Vmax without affecting the apparent Km for the substrate cAMP. Activation by gustin and calmodulin was unaffected by lubrol-PX, trypsin inhibitor, pepstatin A, or leupeptin. In the presence of 1 mM EGTA, gustin activated cAMP PDE 5- to 6-fold, but the activating ability was completely lost after gustin was heated at 100 degrees C for 5 min. In contrast, calmodulin lost all activating ability in the presence of 1 mM EGTA, whereas heating calmodulin at 100 degrees C for 5 min did not affect its activation of cAMP PDEase. Lysophosphatidylcholine-activation of cAMP PDEase, like gustin activation, was unaffected by EGTA, but lysophosphatidylcholine-activation of cAMP PDEase, like calmodulin activation, was unaffected by heating at 100 degrees C for 5 min.

Lesions and saliva-specific antibody responses in rabbits with immediate and delayed hypersensitivity reactions to the bites of Glossina morsitans centralis.

Rabbits exposed to feeding tsetse flies developed cutaneous hypersensitivity responses to fly bites. These responses had characteristics of immediate and delayed type hypersensitivity. Saliva components from the tsetse fly Glossina morsitans centralis were electrophoretically separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Major salivary proteins of 160, 92, 66, 64, 55, 42, 33, 28, and 15 kilodaltons were identified. Separated salivary components were transferred to nitrocellulose filters and probed with lectins and with whole sera and purified IgG from rabbits which had been exposed, via fly feeding, to tsetse antigens for variable periods. Many of the salivary proteins were identified as glycoproteins. Several major salivary proteins were recognized by antibodies from sensitized rabbits.

The allelic forms of three larval salivary proteins from Drosophila melanogaster

Sodium dodecyl sulphate (SDS) gel electrophoresis shows distinct differences in the number and mobility of the major salivary proteins produced by various stocks of Drosophila melanogaster. Genetic analysis showed that the variation was due to the presence of allelic forms of these proteins and demonstrated the absence of certain types of modifying genes. The variation in the mobility of two non-allelic proteins is so large that it is not possible to group variants of these proteins into specific mobility classes. Some results from the genetic analysis of these variants are of relevance to similar analyses of groups of genes determining related proteins in Drosophila.