4066 C. M. H. Anderson and others J Physiol 586.17 In summary, this study describes the ﬁrst demonstration of β-alanine carrier-like function by any cloned transporter. The functional characteristics described here, which are identical to those determined by measurement of amino acid uptake across the luminal surface of ﬂat sheets of rabbit ileal mucosa (Munck, 1985; Munck & Munck, 1990, 1992a,b, 1994, 1995), can account for all β-alanine carrier-like function and emphasize the added value of in situ measurements of physiological function over theoretical predictions of transport protein function based solely upon measurements of mRNA distribution. SLC6A14 was isolated originally from human mammary gland (Sloan & Mager, 1999) and named ATB0,+ due to its similarity in function to the amino acid transport system B0,+, described in mouse blastocysts (Van Winkle et al. 1985). The observations reported in this study demonstrate that SLC6A14 is the β-alanine carrier and that the blastocyst ATB0,+ and intestinal β-alanine carrier are one and the same transport system (Munck & Munck, 1995). The term β-alanine carrier is somewhat inappropriate as a means of identiﬁcation of this intestinal transport system as it has a low afﬁnity for β-alanine, and the intestinal tract contains another transport system for β-alanine namely the H+-coupled amino acid transporter SLC36A1 which is also known variously as system PAT, PAT1 or the imino acid carrier (Thwaites et al. 1993; Chen et al. 2003; Anderson et al. 2004; Thwaites & Anderson, 2007). To reduce confusion in the literature, the term β-alanine carrier should be avoided and the names SLC6A14 and ATB◦,+ adopted to be consistent with descriptions in other tissues (Van Winkle et al. 1985; Munck & Munck, 1994, 1995; Sloan & Mager, 1999; Sloan et al. 2003). References Andersen V & Munck BG (1987). 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J Membr Biol 83, 15–24. C 2008 The Authors. Journal compilation C 2008 The Physiological Society