Hirsch J D, Grillo M, Margolis F L
Brain Res. 1978 Dec 15;158(2):407-22. doi: 10.1016/0006-8993(78)90684-4.
Binding sites for the dipeptide L-carnosine (beta-alanyl-L-histidine) have been detected in membranes prepared from mouse olfactory bulbs. The binding of L-[3H]-carnosine was saturable, reversible and stereospecific and had a Kd of about 770 nM. The stereospecific binding of L-carnosine represented about 30% of the total binding at pH 6.8, and decreased markedly with increasing pH. Binding was stimulated by calcium, unaffected by zinc, magnesium or manganese and inhibited by sodium and potassium. Carnosine binding was sensitive to trypsin and phospholipases A and C, but not to neuraminidase. Nystatin and filipin, which interact with membrane lipids, also interferred with binding. Some peptide analogues of carnosine were potent inhibitors of binding, but a variety of drugs serving as potent inhibitors in other binding systems had no effect on carnosine binding. Carnosine binding to mouse olfactory bulb membranes was 15-fold higher than that seen in membranes prepared from cerebral hemispheres, 5-fold higher than that seen in membranes prepared from cerebral hemispheres, 5-fold higher than in cerebellum membranes and 3-fold higher than in membranes from spinal medulla and the olfactory tubercle-lateral olfactory tract area. Binding sites for 6 other radiolabeled receptor ligands were also detected in bulb membranes. Peripheral deafferentation of the olfactory bulbs by intranasal irrigation with ZnSO4 led to a loss greater than 90% of the L-[3H]carnosine binding in 4--5 days with much smaller losses in binding of the other 6 ligands over a 180-day observation period. This initial loss of carnosine binding after denervation was due to a loss of binding site stereo-specificity followed by a loss of binding sites. The characteristics of the carnosine binding site in olfactory bulb fulfil 6 of the 7 criteria considered relevant for a functional receptor.
在从小鼠嗅球制备的膜中已检测到二肽L-肌肽（β-丙氨酰-L-组氨酸）的结合位点。L-[³H] -肌肽的结合是可饱和的、可逆的且具有立体特异性，解离常数（Kd）约为770 nM。在pH 6.8时，L-肌肽的立体特异性结合约占总结合的30%，并且随着pH升高而显著降低。钙可刺激结合，锌、镁或锰对其无影响，钠和钾则抑制结合。肌肽结合对胰蛋白酶、磷脂酶A和C敏感，但对神经氨酸酶不敏感。与膜脂质相互作用的制霉菌素和菲律宾菌素也会干扰结合。一些肌肽的肽类似物是结合的有效抑制剂，但在其他结合系统中作为有效抑制剂的多种药物对肌肽结合没有影响。肌肽与小鼠嗅球膜的结合比从大脑半球制备的膜中的结合高15倍，比从小脑膜中制备的膜中的结合高5倍，比从脊髓和嗅结节 - 外侧嗅束区域的膜中的结合高3倍。在嗅球膜中还检测到了其他6种放射性标记受体配体的结合位点。通过用ZnSO₄进行鼻内冲洗对嗅球进行外周去传入神经支配，在4 - 5天内导致L-[³H] -肌肽结合损失超过90%，而在180天的观察期内其他6种配体的结合损失要小得多。去神经支配后肌肽结合的这种初始损失是由于结合位点立体特异性的丧失，随后是结合位点的丧失。嗅球中肌肽结合位点的特征符合被认为与功能性受体相关的7条标准中的6条。
