Antibodies to ATPase Enzymes - Product Review 12

Introduction

ATPase proteins are enzymes which are able to supply energy by cleaving ATP into ADP and phosphate. This energy can be used for transport of ions into or out of the cell against a concentration gradient. There are several forms of membrane bound ATPase enzymes responsible for export or import of different ions.

The sodium/potassium ATPase is an integral membrane enzyme found in all cells of higher organisms and is responsible for the ATP-dependent transport of sodium and potassium across the cell membrane. This membrane-bound enzyme is related to a number of other ATPases including sarcoplasmic and endoplasmic reticulum calcium ATPase (SERCA) and plasma membrane calcium ATPase (PMCA). The sodium/potassium ATPase consists of a large, multipass, transmembrane catalytic subunit, termed the alpha subunit, and an associated smaller glycoprotein, termed the beta subunit. Studies indicate that there are three isoforms of the alpha subunit (alpha 1, alpha 2, alpha 3) and two isoforms of the beta subunit (beta 1 and beta 2) encoded by two multigene families. The different isoforms of the sodium/potassium ATPase exhibit tissue-specific and developmental patterns of expression. The alpha 1 and beta mRNAs are present in all cell types examined, whereas the alpha 2 and alpha 3 mRNAs exhibit a more restricted pattern of cell-specific expression. The alpha subunit has been found in kidney, brain, heart, and to a lesser extent liver, skeletal and smooth muscle.

The calcium pump of the plasma membrane, termed PMCA ATPase, pumps calcium from the cytosol to the extracellular space. There are four different genes encoding PMCA ATPase and studies have revealed 20 isoforms of the pump generated by alternate splicing of the primary gene products. mRNA distribution studies show that gene products 1 and 4 are transcribed in most tissues, however, products 2 and 3 are more tissue specific. Transcription of the splicing variants has also been found to be tissue specific. In the pancreas, where insulin secretion is calcium dependent, the beta cells only express the 4b isoform, however the alpha and gamma cells express both 4a and 4b isoforms. Studies have also shown that different splice variants have different affinities for calcium and calmodulin.

ATP dependent calcium pumps are responsible, in part, for the maintenance of low cytoplasmic free calcium concentrations. The ATP pumps that reside in intracellular organelles are encoded by a family of structurally related enzymes, termed the sarcoplasmic or endoplasmic reticulum calcium ATPases (SERCA). The SERCA1 gene is exclusively expressed in type II (fast) skeletal muscle. The SERCA2 gene is subject to tissue dependent processing which is responsible for the generation of SERCA2a muscle-specific form expressed in type I (slow) skeletal, cardiac and smooth muscle and the SERCA2b isoform expressed in all cell types. The SERCA3 gene is not as well characterized and is found in non-muscle cells.

The hydrogen/potassium ATPase, or gastric proton pump, belongs to a family of P-type cation-transporting ATPases. This family of ATPases shares a number of functional and structural similarities including the common feature of consisting of an alpha and beta subunit. Like the ubiquitous sodium/potassium ATPase, the hydrogen/potassium ATPase consists of a large transmembrane catalytic subunit, termed the alpha- subunit which contains sites for ATP binding and phosphorylation, and an associated smaller glycoprotein, termed the beta-subunit which may play a role in maintaining the structural and functional integrity of the complex.

Antibody Tools for Detection of Membrane Bound ATPase Enzymes

Acris Antibodies offers a wide range of antibodies specific for the different types of membrane bound ATPase enzymes and their respective isoforms. Monoclonal and polyclonal antibodies useful for multiple applications are listed in the table below. Species reactivity is broad in most cases due to high conservation of these proteins. Pricing and product informations are available using the links provided.

Available products

ATPase, PMCA, SERCA antibody