From 62f8be2f3bc9193b04cf4d4b846f6c8796b242a7 Mon Sep 17 00:00:00 2001
From: Charles Plessy <plessy@riken.jp>
Date: Thu, 17 May 2018 13:35:31 +0900
Subject: [PATCH] The cap is reverse-transcribed.

---
 tags/reverse_transcription.mdwn | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/tags/reverse_transcription.mdwn b/tags/reverse_transcription.mdwn
index 8719370c..b8914e01 100644
--- a/tags/reverse_transcription.mdwn
+++ b/tags/reverse_transcription.mdwn
@@ -35,6 +35,15 @@ transcriptases have a TdT activity.
    Activity increased with concentration for MMLV.  (High-concentration AMV was
    not available.)
 
+ - [[Oz-Gleenberg et al, 2011|biblio/22035236]] showed that the the reverse
+   transcriptase of the long terminal repeat retrotransposon Tf1, like other
+   DNA polymerases, also adds non-templated As to blunt DNA duplexes.
+
+### Templated TdT activity
+
+Surprisingly, reverse transcriptases can also extend cDNAs using a single
+nucleotide as a template.
+
  - Following an initial observation of [[Clark et al (1987)|biblio/3323527]] on
    the Klenow fragment, [[Ohtsubo et al, 2017a|biblio/28150748]] showed that
    specific tailing is enhanced by the complementary dNMP (C enhanced by dGMP,
@@ -45,6 +54,28 @@ transcriptases have a TdT activity.
    tailing when longer reaction times are allowed ([[Ohtsubo et al.,
    2017b|biblio/28747695]]).
 
+
+### The 5′ cap is reverse-transcribed
+
+ - [[Hirzmann et al., 1993|biblio/8346046]] observed the presence of an extra G
+   at the 5′ end of cDNA clones, and concluded that the cap can be
+   reverse-transcribed.  They supported their conclusion with molecular modelling.
+
+ - [[Volloch et al, 1995|biblio/8534373]] studied cap transcription (but I could
+   not access the article).
+
+ - [[Ohtake et al, 2004|biblio/15500255]] synthethised RNAs with A-caps and
+   showed that they are reverse-transcribed as Ts.
+
+ - [[Lavie et al, 2004|biblio/15520289]] found extra Gs at the ends of genomic
+   sequences of retrotransposons, showing that endogenous reverse-transcriptases
+   also reverse-transcribe the cap.
+
+ - [[Zhang et al, 2017|biblio/28673998] published a structure of an RNA-GpppG
+   complex that suggests that a m7GpppNm / DNA duplex could form during the
+   reverse-transcription of the cap
+
+
 ### Reverse-transcriptases tolerate terminal mismatches
 
  - Reported by [[Mizuno et al., 1999|biblio/9973624]].
-- 
2.47.3