Sharrow Scott D, Vaughn Jeffrey L, Zídek Lukás, Novotny Milos V, Stone Martin J
Institute for Pheromone Research and Department of Chemistry, Indiana University, Bloomington, Indiana 47405-0001, USA.
Protein Sci. 2002 Sep;11(9):2247-56. doi: 10.1110/ps.0204202.
Mouse major urinary proteins (MUPs) have been proposed to play a role in regulating the release and capture of pheromones. Here, we report affinity measurements of five recombinant urinary MUP isoforms (MUPs-I, II, VII, VIII, and IX) and one recombinant nasal isoform (MUP-IV) for each of three pheromonal ligands, (+/-)-2-sec-butyl-4,5-dihydrothiazole (SBT), 6-hydroxy-6-methyl-3-heptanone (HMH), and (+/-)dehydro-exo-brevicomin (DHB). Dissociation constants for all MUP-pheromone pairs were determined by isothermal titration calorimetry, and data for SBT were corroborated by measurements of intrinsic protein fluorescence. We also report the isolation of MUP-IV protein from mouse nasal extracts, in which MUP-IV mRNA has been observed previously. The affinity of each MUP isoform for SBT (K(d) approximately 0.04 to 0.9 micro M) is higher than that for DHB (K(d) approximately 26 to 58 micro M), which in turn is higher than that for HMH (K(d) approximately 50 to 200 micro M). Isoforms I, II, VIII, and IX show very similar affinities for each of the ligands. MUP-VII has approximately twofold higher affinity for SBT but approximately twofold lower affinity for the other pheromones, whereas MUP-IV has approximately 23-fold higher affinity for SBT and approximately fourfold lower affinity for the other pheromones. The variations in ligand affinities of the MUP isoforms are consistent with structural differences in the binding cavities of the isoforms. The data indicate that the concentrations of available pheromones in urine may be influenced by changes in the expression levels of urinary MUPs or the excretion levels of other MUP ligands. The variation in pheromone affinities of the urinary MUP isoforms provides only limited support for the proposal that MUP heterogeneity plays a role in regulating profiles of available pheromones. However, the binding data support the proposed role of nasal MUPs in sequestering pheromones and possibly transporting them to their receptors.
小鼠主要尿蛋白（MUPs）被认为在调节信息素的释放和捕获中发挥作用。在此，我们报告了五种重组尿MUP亚型（MUPs-I、II、VII、VIII和IX）和一种重组鼻亚型（MUP-IV）对三种信息素配体[（+/-）-2-仲丁基-4,5-二氢噻唑（SBT）、6-羟基-6-甲基-3-庚酮（HMH）和（+/-）脱氢-外向-短叶松素（DHB）]的亲和力测量结果。通过等温滴定量热法测定了所有MUP-信息素对的解离常数，并且通过测量蛋白质固有荧光对SBT的数据进行了确证。我们还报告了从小鼠鼻提取物中分离出MUP-IV蛋白，此前在该提取物中已观察到MUP-IV mRNA。每种MUP亚型对SBT的亲和力（K(d)约为0.04至0.9 μM）高于对DHB的亲和力（K(d)约为26至58 μM），而对DHB的亲和力又高于对HMH的亲和力（K(d)约为50至200 μM）。亚型I、II、VIII和IX对每种配体的亲和力非常相似。MUP-VII对SBT的亲和力大约高两倍，但对其他信息素的亲和力大约低两倍，而MUP-IV对SBT的亲和力大约高23倍，对其他信息素的亲和力大约低四倍。MUP亚型的配体亲和力变化与亚型结合腔的结构差异一致。数据表明，尿液中可用信息素的浓度可能受尿MUP表达水平变化或其他MUP配体排泄水平的影响。尿MUP亚型信息素亲和力的变化仅为MUP异质性在调节可用信息素谱中发挥作用这一观点提供了有限支持。然而，结合数据支持了鼻MUP在隔离信息素并可能将它们转运至其受体中所提出的作用。
