Why do male mice spit soluble enzymes that hydrolyze extracellular nucleotides? Focus on "Prostatic acid phosphatase is the main acid phosphatase with 5'-ectonucleotidase activity in the male mouse saliva and regulates salivation".

THE 5=-ECTONUCLEOTIDASES FOUND on the surface of most mammalian cells and in blood serum serve as a source of adenosine derived from extracellular nucleotide degradation (11). The 5=-ectonucleotidases are phosphatases whose substrate is extracellular adenosine 5=-monophosphate (AMP) generated from adenosine 5=-triand diphosphates (ATP and ADP) released from injured tissues to stimulate cellular responses via P2 purinergic receptors (7). A recent study by Quintero et al. (10) investigated prostatic acid phosphatase (PAP), a 5=-ectonucleotidase that plays a role in the development of adenocarcinoma of the prostate gland. These authors showed that PAP exists as two alternative splice variants, a transmembrane prostatic acid phosphatase (TMPAP) and secreted PAP (sPAP). TMPAP and sPAP are distinguished functionally from other 5=-nucleotidases through inhibition by L ( ) tartrate, Address for reprint requests and other correspondence: G. A. Weisman, Dept. of Biochemistry, 540E Life Sciences Center, 1201 Rollins Road, Univ. of Missouri, Columbia, MO 65211-7310 (e-mail: weismang@missouri. edu).