Cloning and expression of the alveolar type II cell P2u-purinergic receptor.

Adenosine triphosphate (ATP) regulates surfactant phospholipid secretion from alveolar type II cells by interacting with P2-purinoceptors on the alveolar type II cell surface. To further characterize regulation of surfactant secretion, we have cloned the type II cell P2u-purinoceptor and expressed a functional receptor in an unrelated cell line. The coding sequence of the P2u clone isolated from a type II cell cDNA library was 1.1 kb, encoding a putative protein of 374 amino acids. The putative protein demonstrated > 97% homology with the P2u-purinoceptor previously identified in the hybrid neuroblastoma x glioma cell line, NG 108-15, 87% homology to the recently cloned human P2u-purinoceptor, and 34% homology to the P2u-purinoceptor cloned from chicken brain. The putative type II cell P2u protein contains seven membrane-spanning domains, characteristic of G-protein-coupled receptors. The type II cell P2u-purinoceptor nucleotide sequence also demonstrated > 95% homology to the nucleotide sequence of the N...