Müller H, Orwig K E, Soares M J
Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City 66160-7401, USA.
Biochim Biophys Acta. 1998 Mar 13;1396(3):251-8. doi: 10.1016/s0167-4781(97)00218-2.
The prolactin (PRL) family consists of a collection of genes expressed in the uterus, placenta, and anterior pituitary. These cytokines/hormones participate in the control of maternal-fetal adaptations to pregnancy. In this report, we establish the presence of two new members of the mouse PRL family. Novel expressed sequence tags (ESTs) with significant homology to PRL were isolated from embryonic, ectoplacental cone, and placental cDNA libraries. The cDNAs were sequenced and compared to other members of the PRL family. The two new cDNAs were assigned to the PRL family based on sequence homology and were referred to as PRL-like protein-F (PLP-F) and PRL-like protein-G (PLP-G). PLP-F cDNA encodes for a predicted 267 amino acid protein containing a 30 amino acid signal peptide and three putative N-linked glycosylation sites. PLP-G cDNA encodes for a predicted 266 amino acid protein containing a 30 amino acid signal peptide and six putative N-linked glycosylation sites. Sequence alignments of these proteins with other members of the PRL family suggest some unique features. Both sequences contain an extra amino acid segment located between exons two and three of the prototypical PRL gene and a nine amino acid carboxy terminal extension. PLP-F contained an additional 15 amino acid region situated between exons four and five of the prototypical PRL gene. Both PLP-F and PLP-G mRNAs were expressed in the placenta but not in other tissues (uterus, brain, thymus, heart, lung, diaphragm, liver, kidney, and ovary). In summary, the two newly identified members share approximately 50% amino acid sequence identity, are specifically expressed in the placenta, and represent a new subfamily within the PRL family.
催乳素（PRL）家族由在子宫、胎盘和垂体前叶表达的一组基因组成。这些细胞因子/激素参与控制母体-胎儿对妊娠的适应性变化。在本报告中，我们确定了小鼠PRL家族的两个新成员。从胚胎、外胎盘锥和胎盘cDNA文库中分离出与PRL具有显著同源性的新型表达序列标签（EST）。对这些cDNA进行测序，并与PRL家族的其他成员进行比较。基于序列同源性，将这两个新的cDNA归入PRL家族，分别称为催乳素样蛋白-F（PLP-F）和催乳素样蛋白-G（PLP-G）。PLP-F cDNA编码一个预测的267个氨基酸的蛋白质，含有一个30个氨基酸的信号肽和三个推定的N-连接糖基化位点。PLP-G cDNA编码一个预测的266个氨基酸的蛋白质，含有一个30个氨基酸的信号肽和六个推定的N-连接糖基化位点。这些蛋白质与PRL家族其他成员的序列比对显示出一些独特特征。两个序列均在典型PRL基因的外显子2和外显子3之间包含一个额外的氨基酸片段以及一个9个氨基酸的羧基末端延伸。PLP-F在典型PRL基因的外显子4和外显子5之间还含有一个额外的15个氨基酸区域。PLP-F和PLP-G的mRNA均在胎盘中表达，但在其他组织（子宫、脑、胸腺、心脏、肺、膈肌、肝脏、肾脏和卵巢）中不表达。总之，这两个新鉴定的成员氨基酸序列同一性约为50%，在胎盘中特异性表达，代表PRL家族中的一个新亚家族。
