A signal peptide (sometimes referred to as signal sequence, targeting signals, localization signals, localization sequence, transit peptides, leader sequence or leader peptide) is a short (5-30 amino acids long) peptide present at the N-terminus of the majority of newly synthesized proteins that are destined towards the secretory pathway.
中文的翻译是 “信号肽”，根据 信号肽-wikipedia 有：
信号肽是引导新合成的蛋白质向分泌通路转移的短（长度 5-30 个氨基酸）肽链。
顺便还提了一下历史。”signal” 语出 Günter Blobel (1999 Nobel Prize winner in Physiology or Medicine) 和 B. Dobberstein 于 1975 年发表的 Transfer of proteins across membranes. II. Reconstitution of functional rough microsomes from heterologous components。原文提出了一个 “signal hypothesis”，而且用的原词是 “signal sequence”，比如：
It is possible that the ribosomereleased chains have achieved a sufficient degree of folding so that their signal sequence (in particular if hydrophobic) is buried within the molecule.
此外还有一个概念是 target peptide，应该也是同样的概念（好烦！）。因为 Target peptide - wikipedia 举的一个例子是：
A nuclear localization signal (NLS) is a target peptide that directs proteins to the nucleus and is often a unit consisting of five basic, positively-charged amino acids. The NLS normally is located anywhere on the peptide chain.
还给出了 NLS 的 AA 序列：
-Pro-Pro-Lys-Lys-Lys-Arg-Lys-Val-。这么一来 “signal motif” 就好理解了。比如 NLS 的 PY-NLS motif, so named because of the proline-tyrosine amino acid pairing in it.
顺便说一下 Secretory pathway，注意不要写错别字：
- secret: [ˈsi:krit]
- secretary: [ˈsekrətri] or [ˈsekrəteri]
- secrete: [sɪˈkri:t], 分泌
- secretory: [sɪ’kri:tərɪ]
The secretory pathway is a series of steps a cell uses to move proteins out of the cell; a process known as secretion
最后说一下 Protein targeting。根据 Protein targeting - wikipedia 有：
Protein targeting or protein sorting is the biological mechanism by which proteins are transported to the appropriate destinations in the cell or outside of it.
所以 Protein targeting 指的是整个这个 translocation 的机制。