THE MAMMALIAN GENE OF ACETYLCHOLINESTERASE-ASSOCIATED COLLAGEN

The collagen-tailed or asymmetric forms (A) represent a major componen t of acetylcholinesterase (AChE) in the neuromuscular junction of high er vertebrates. They are hetero-oligomeric molecules, in which tetrame rs of catalytic subunits of type T (AChE(T)) are attached to the subun its of a triple-stranded collagen ''tail.'' We report the cloning of a t rat AChE-associated collagen subunit, Q. We show that collagen tails are encoded by a single gene, COLQ. The ColQ subunits form homotrimer s and readily form collagen-tailed AChE, when coexpressed with rat ACh E(T). We found that the same ColQ subunits are incorporated, in vivo, in asymmetric forms of both AChE and butyrylcholinesterase. A splice v ariant from the COLQ gene encodes a proline-rich AChE attachment domai n without the collagen domain but does not represent the membrane anch or of the brain tetramer. The COLQ gene is expressed in cholinergic ti ssues, brain, muscle, and heart, and also in noncholinergic tissues su ch as lung and testis.