RESUMO
Several odorant-binding proteins (OBP) have been previously purified from the nasal mucosa of the old world porcupine Hystrix cristata. In this paper, we report their N-terminal amino-acid sequences and accurate molecular weights, as measured by electrospray mass spectrometry. The partial amino acid sequences reveal significant similarity with OBPs of other mammalian species and segregate the eight proteins purified into two subclasses. Mass spectrometry has revealed microheterogeneity among the proteins belonging to each of these two groups, suggesting a total number of OBPs of at least nine. The molecular weight differences between OBPs cannot be readily accounted for by common post-translation modifications and indicate different gene products. Such a large number of different OBPs may represent further support to an odour discriminating role for these proteins.
Assuntos
Espectrometria de Massas , Fragmentos de Peptídeos/química , Receptores Odorantes/química , Roedores , Análise de Sequência , Sequência de Aminoácidos , Animais , Dados de Sequência Molecular , Peso Molecular , Mucosa Olfatória/químicaRESUMO
1. Eight new proteins have been identified and purified from the nasal tissue of the old-world porcupine. 2. All of them show good binding activity to tritiated 2-isobutyl-3-methoxypyrazine. 3. They show values of molecular mass, in denaturing conditions, between 18 and 23 kDa, and of isoelectric points between 4.2 and 4.6. 4. This represents the first example of more than two odorant-binding proteins (OBPs) found in the same animal species and could support a discriminating function of these proteins in the process of odour perception.
Assuntos
Proteínas de Transporte/isolamento & purificação , Cavidade Nasal/química , Mucosa Olfatória/química , Pirazinas/metabolismo , Receptores Odorantes , Roedores , Aminoácidos/análise , Animais , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Eletroforese em Gel de Poliacrilamida , Feminino , Ponto Isoelétrico , Peso Molecular , OdorantesRESUMO
1. Two soluble proteins, with good affinity to tritiated 2-isobutyl-3-methoxypyrazine, have been purified from mouse nasal mucosa. 2. The first protein is a heterodimer with subunits of apparent M(r) 18 and 19 kDa and isoelectric point of 4.9; the second is a monomer of M(r) 21 kDa and isoelectric point of 4.8. 3. The characteristics of these binding proteins are compared with those of the other known OBPs and urinary proteins and their putative role is discussed.