Molecular cloning of cAMP-dependent protein kinase catalytic subunit isoforms from the lone star tick, Amblyomma americanum (L.)

The salivary glands of ixodid ticks are central to tick feeding and to surv ival during off-host periods. They produce and secrete a number of molecule s critical to maintaining the complex host-vector interface and to maintain ing osmotic balance. We have previously shown that a cyclic AMP-dependent p rotein kinase (cAPK) is involved in the mechanism of salivary gland secreti on. We have now cloned cDNAs encoding three isoforms of the catalytic subun it (cAPK-C) of the cAPK from Amblyomma americanum, which are probably produ ced from alternative RNA processing of a single cAPK-C gene. The cDNAs cont ain unique N-termini of variable lengths that are linked to a common region containing the alpha A helix, catalytic core, and a C-terminal tail. The c ommon region is highly similar to both insect and vertebrate cAPK-Cs. We ha ve examined mRNA profiles in whole ticks and in isolated salivary glands th roughout feeding and find that a single cAPK-C isoform is expressed in the salivary glands of both unfed and feeding females. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.