[Tex/LaTex] Arrow accented with a dot (natural transformation)

Question

In Mac Lane's "Categories for the Working Mathematician" I came across an arrow accented above with a dot, indicating a natural transformation. I failed to find an existing symbol for this. It looks something like

$$\overset{\bullet}{\longrightarrow}$$

but the dot is smaller and close to the arrow. I want to avoid if possible constructing a custom symbol. Does something like this exist? DeteXify could not find one.

Answer 1

This is similar to Mico's, but doesn't use \ooalign, since an approach without overlapping rules seems better:

\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}
\newcommand{\naturalto}{%
  \mathrel{\vbox{\offinterlineskip
    \mathsurround=0pt
    \ialign{\hfil##\hfil\cr
      \normalfont\scalebox{1.2}{.}\cr
%      \noalign{\kern-.05ex}
      $\longrightarrow$\cr}
  }}%
}
\begin{document}
$F\naturalto G\overset{\text{\normalsize.}}\longrightarrow H$
\end{document}

This won't scale in sub/superscripts, but I can't see this as a real limitation. The commented line shows where to act for raising or lowering the dot. The second arrow is just for comparison.