Elphick Maurice R
Queen Mary University of London, School of Biological & Chemical Sciences, Mile End Road, London E1 4NS, UK.
Gen Comp Endocrinol. 2014 Sep 1;205:23-35. doi: 10.1016/j.ygcen.2014.02.012. Epub 2014 Feb 28.
The SALMFamides are a family of neuropeptides that occur in species belonging to the phylum Echinodermata. The prototypes for this neuropeptide family (S1 and S2) were discovered in starfish but subsequently SALMFamides were identified in other echinoderms. There are two types of SALMFamides: L-type, which have the C-terminal motif SxLxFamide, and F-type, which have the C-terminal motif SxFxFamide. They are derived from two types of precursor proteins: an L-type SALMFamide precursor, which comprises only L-type or L-type-like SALMFamides and an F-type SALMFamide precursor, which contains several F-type or F-type-like SALMFamides and, typically, one or more L-type SALMFamides. Thus, SALMFamides occur as heterogeneous mixtures of neuropeptides - a SALMFamide salmagundi. SALMFamides are produced by distinct populations of neurons in echinoderm larval and adult nervous systems and are present in the innervation of neuromuscular organs. Both L-type and F-type SALMFamides cause muscle relaxation in echinoderms and, for example, in starfish this effect of SALMFamides may mediate neural control of cardiac stomach eversion in species that feed extra-orally (e.g., Asterias rubens). The SALMFamide S1 also causes inhibition of neural release of a relaxin-like gonadotropin in the starfish Asterina pectinifera. An important issue that remains to be resolved are the relationships of SALMFamides with neuropeptides that have been identified in other phyla. However, it has been noted that the C-terminal SxLxFamide motif of L-type SALMFamides is a feature of some members of a bilaterian neuropeptide family that includes gonadotropin-inhibitory hormone (GnIH) in vertebrates and SIFamide-type neuropeptides in protostomes. Similarly, the C-terminal FxFamide motif of F-type SALMFamides is a feature of vertebrate QRFP (26RFa)-type neuropeptides. These sequence similarities may provide a basis for molecular identification of receptors that mediate effects of SALMFamides. Furthermore, analysis of the actions of the heterogeneous mixtures of SALMFamides that occur in echinoderms may provide new insights into the physiological significance of the general phenomenon of precursor proteins that give rise to neuropeptide "cocktails".
SALMFamides是一类神经肽，存在于棘皮动物门的物种中。这个神经肽家族的原型（S1和S2）是在海星中发现的，但随后在其他棘皮动物中也鉴定出了SALMFamides。SALMFamides有两种类型：L型，其C末端基序为SxLxFamide；F型，其C末端基序为SxFxFamide。它们源自两种类型的前体蛋白：一种L型SALMFamide前体，仅包含L型或L型样SALMFamides；以及一种F型SALMFamide前体，包含几种F型或F型样SALMFamides，通常还包含一个或多个L型SALMFamides。因此，SALMFamides以神经肽的异质混合物形式存在——一种SALMFamide什锦菜。SALMFamides由棘皮动物幼虫和成虫神经系统中不同的神经元群体产生，并存在于神经肌肉器官的神经支配中。L型和F型SALMFamides都会导致棘皮动物的肌肉松弛，例如，在海星中，SALMFamides的这种作用可能介导了通过口外摄食的物种（如红海星）中心脏胃外翻的神经控制。SALMFamide S1还会抑制海星日本海燕中一种松弛素样促性腺激素的神经释放。一个有待解决的重要问题是SALMFamides与在其他门中已鉴定出的神经肽之间的关系。然而，已经注意到L型SALMFamides的C末端SxLxFamide基序是双侧神经肽家族某些成员的一个特征，该家族包括脊椎动物中的促性腺激素抑制激素（GnIH）和原口动物中的SIFamide型神经肽。同样，F型SALMFamides的C末端FxFamide基序是脊椎动物QRFP（26RFa）型神经肽的一个特征。这些序列相似性可能为介导SALMFamides作用的受体的分子鉴定提供基础。此外，对棘皮动物中出现的SALMFamides异质混合物作用的分析可能会为产生神经肽“鸡尾酒”的前体蛋白这一普遍现象的生理意义提供新的见解。
