title: Functional characterization of transmembrane adenylyl cyclases from the honeybee brain.
abstract: The second messenger cAMP has a pivotal role in animals' physiology and behavior. Intracellular concentrations of cAMP are balanced by cAMP-synthesizing adenylyl cyclases (ACs) and cAMP-cleaving phosphodiesterases. Knowledge about ACs in the honeybee (Apis mellifera) is rather limited and only an ortholog of the vertebrate AC3 isoform has been functionally characterized, so far. Employing bioinformatics and functional expression we characterized two additional honeybee genes encoding membrane-bound (tm)ACs. The proteins were designated AmAC2t and AmAC8. Unlike the common structure of tmACs, AmAC2t lacks the first transmembrane domain. Despite this unusual topography, AmAC2t-activity could be stimulated by norepinephrine and NKH477 with EC(50s) of 0.07 μM and 3 μM. Both ligands stimulated AmAC8 with EC(50s) of 0.24 μM and 3.1 μM. In brain cryosections, intensive staining of mushroom bodies was observed with specific antibodies against AmAC8, an expression pattern highly reminiscent of the Drosophila rutabaga AC. In a current release of the honeybee genome database we identified three additional tmAC- and one soluble AC-encoding gene. These results suggest that (1) the AC-gene family in honeybees is comparably large as in other species, and (2) based on the restricted expression of AmAC8 in mushroom bodies, this enzyme might serve important functions in honeybee behavior.
authors.affiliation: Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Balfanz
authors.forename: Petra
authors.initials: P
authors.lastname: Ehling
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wachten
authors.forename: Nadine
authors.initials: N
authors.lastname: Jordan
authors.forename: Joachim
authors.initials: J
authors.lastname: Erber
authors.forename: Samir
authors.initials: S
authors.lastname: Mujagic
authors.forename: Arnd
authors.initials: A
authors.lastname: Baumann
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001516:Bees / Q000201:enzymology* / Q000235:genetics; D001921:Brain / Q000201:enzymology; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D005810:Multigene Family; D012689:Sequence Homology, Nucleic Acid
chemical_list: D019476:Insect Proteins; D000262:Adenylyl Cyclases