Hepatic glycogen-targeting subunit G(L) of protein phosphatase-1 (PP1), which is encoded by the gene Ppp1r3b, is one of a family of proteins that target PP1 to glycogen and regulate its activity on enzymes of glycogen metabolism. G(L) is primarily expressed in the liver where it promotes hepatic glycogen synthesis in response to insulin. Here, we show that G(L) is highly expressed in embryonic mouse lungs. G(L) utilizes two alternative promoters and 5' non-coding exons, which produce at least three alternatively spliced transcripts that encode identical proteins. Expression of G(L) in the lung is detectable as early as embryonic day (E) 12.5 and increases by E16.5, however, it declines before birth. In situ hybridization of mouse embryonic lung revealed that G(L) is expressed in bronchial epithelial cells. Thus, the temporal and spatial expression of G(L) in the lung suggests that it has a potential role in glycogen metabolism during lung development. (c) 2006 Elsevier Inc. All rights reserved.