Chemicals and Drugs Commons^™

Physiological Roles Of Mammalian Transmembrane Adenylyl Cyclase Isoforms, Katrina F. Ostrom, Justin E. Lavigne, Tarsis F. Brust, Roland Seifert, Carmen Dessauer, Val J. Watts, Rennolds S. Ostrom

Pharmacy Faculty Articles and Research

Adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. Mammals possess nine isoforms of transmembrane ACs, dubbed AC1-9, that serve as major effector enzymes of G protein-coupled receptors. The transmembrane ACs display varying expression patterns across tissues, giving potential for them having a wide array of physiologic roles. Cells express multiple AC isoforms, implying that ACs have redundant functions. Furthermore, all transmembrane ACs are activated by Gα_s so it was long assumed that all ACs are activated by Gα_s-coupled GPCRs. AC isoforms partition to different microdomains of the plasma membrane and form …

Subtype-Selective Positive Modulation Of KCa 2 Channels Depends On The Ha/Hb Helices, Young-Woo Nam, Meng Cui, Naglaa Salem, Razan Orfali, Misa Nguyen, Grace Yang, Mohammad Asikur Rahman, Judy Lee, Miao Zhang

Pharmacy Faculty Articles and Research

Background and Purpose

In the activated state of small-conductance Ca2+-activated potassium (KCa 2) channels, calmodulin interacts with the HA/HB helices and the S4-S5 linker. CyPPA potentiates KCa 2.2a and KCa 2.3 channel activity but not the KCa 2.1 and KCa 3.1 subtypes.

Experimental Approach

Site-directed mutagenesis, patch-clamp recordings and in silico modeling were utilized to explore the structural determinants for the subtype-selective modulation of KCa 2 channels by CyPPA.

Key Results

Mutating residues in the HA (V420) and HB (K467) helices of KCa 2.2a channels to their equivalent residues in KCa 3.1 channels diminished the potency of CyPPA. CyPPA elicited …