text: user1771: I am reading Tang et al. (2009).
  In the method description it is stated that:
  
  A single cell is manually picked under a microscope and lysed. Then mRNAs are reverse-transcribed into cDNAs using a poly(T) primer with anchor sequence (UP1) and unused primers are digested.
  
  What is an anchor sequence in this case?
  
  Tang, F. et al. mRNA-Seq whole-transcriptome analysis of a single cell. Nat. Methods 6, 377–382 (2009).
  
  
  user73: As shown in figure 1 of that paper, the anchor sequence is additional sequence that is added to the end of the polyT primer that provides a known and non-target binding site for additional PCR reactions. I gave a presentation about a month ago about the process that Oxford Nanopore Technology use in their strand-switching cDNA kit, which may be useful for understanding the process used by Tang et al.. Here are my strand-switch/PCR images from that presentation:
  
  PolyT primer addition, with mismatched anchor sequence
  
  
  
  Strand switch primer addition, with overhanging anchor sequence
  
  
  
  PCR amplification, using primers that are complementary to the anchor sequences
  
  
  In the case of the Tang et al. paper, they use a polyA-tailing method for strand-switching, but the process is essentially the same.
  
original_text: 1771: <p>I am reading Tang et al. (2009).</p>
  
  <p>In the method description it is stated that:</p>
  
  <blockquote>
    <p>A single cell is manually picked under a microscope and lysed. Then mRNAs are reverse-transcribed into cDNAs using a poly(T) primer <strong>with anchor sequence</strong> (UP1) and unused primers are digested.</p>
  </blockquote>
  
  <p>What is an anchor sequence in this case?</p>
  
  <ol>
  <li>Tang, F. et al. <a href="https://www.nature.com/articles/nmeth.1315" rel="nofollow noreferrer">mRNA-Seq whole-transcriptome analysis of a single cell</a>. Nat. Methods 6, 377–382 (2009).</li>
  </ol>
   73: <p>As shown in figure 1 of that paper, the anchor sequence is additional sequence that is added to the end of the polyT primer that provides a known and non-target binding site for additional PCR reactions. I gave <a href="https://f1000research.com/slides/7-251" rel="nofollow noreferrer">a presentation</a> about a month ago about the process that Oxford Nanopore Technology use in their strand-switching cDNA kit, which may be useful for understanding the process used by Tang <em>et al.</em>. Here are my strand-switch/PCR images from that presentation:</p>
  
  <ol>
  <li>PolyT primer addition, with mismatched anchor sequence</li>
  </ol>
  
  <p><a href="https://i.stack.imgur.com/rpSO9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rpSO9.png" alt="PolyT primer addition, with mismatched anchor sequence"></a></p>
  
  <ol start="2">
  <li>Strand switch primer addition, with overhanging anchor sequence</li>
  </ol>
  
  <p><a href="https://i.stack.imgur.com/lK3qh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lK3qh.png" alt="Strand switch primer addition, with overhanging anchor sequence"></a></p>
  
  <ol start="3">
  <li>PCR amplification, using primers that are complementary to the anchor sequences</li>
  </ol>
  
  <p><a href="https://i.stack.imgur.com/QnIow.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QnIow.png" alt="PCR amplification using complementary primers"></a></p>
  
  <p>In the case of the Tang <em>et al.</em> paper, they use a polyA-tailing method for strand-switching, but the process is essentially the same.</p>
  