Miceli C, La Terza A, Bradshaw R A, Luporini P
Department of Molecular, Cellular, and Animal Biology, University of Camerino, Italy.
Proc Natl Acad Sci U S A. 1992 Mar 1;89(5):1988-92. doi: 10.1073/pnas.89.5.1988.
In the ciliate Euplotes raikovi, the same cell that secretes the pheromone Er-1, a polypeptide of 40 amino acids derived from a precursor (prepro-Er-1) of 75 amino acids, also produces a polypeptide of 130 amino acids, of which the 75 residues at the carboxyl terminus are identical to those of prepro-Er-1 and the 55 residues at the amino terminus form a new sequence. This larger Er-1 isoform is retained in membranes, where it may function as a binding site for soluble Er-1 in a mechanism of autocrine secretion. Membrane-bound and soluble Er-1 are translated from two mRNAs that apparently originate from a common micronuclear and/or macronuclear gene through alternative elimination of intervening sequences. This finding suggests that single genes responsible for the generation of isoform diversity in polypeptide hormones are present even in single-celled eukaryotes.
在纤毛虫类的赖科夫真核游仆虫（Euplotes raikovi）中，分泌信息素Er-1（一种由75个氨基酸的前体（前原Er-1）衍生而来的40个氨基酸的多肽）的同一个细胞，还产生一种130个氨基酸的多肽，其中羧基末端的75个残基与前原Er-1的残基相同，而氨基末端的55个残基则形成一个新序列。这种更大的Er-1同种型保留在膜中，在自分泌机制中它可能作为可溶性Er-1的结合位点发挥作用。膜结合型和可溶性Er-1由两种mRNA翻译而来，这两种mRNA显然通过选择性去除间隔序列，起源于一个共同的小核和/或大核基因。这一发现表明，即使在单细胞真核生物中，也存在负责多肽激素同种型多样性产生的单个基因。
