  For a fixed prequantum line bundle $L$ over a hyperK\"ahler manifold $X$, we
find a natural $\operatorname{Sp}(1)$-action on $\Omega^*(X, L)$ intertwining a
twistor family of $\operatorname{Spin}^{\operatorname{c}}$-Dirac Laplacians on
the spaces of $L$-valued $(0, *)$-forms on $X$, noting that $L$ is holomorphic
for only one complex structure in the twistor family. This establishes a
geometric quantization of $X$ via Gukov-Witten brane quantization and leads to
a proposal of a mathematical definition of
$\operatorname{Hom}(\overline{\mathcal{B}}_{\operatorname{cc}},
\mathcal{B}_{\operatorname{cc}})$ for the canonical coisotropic A-brane
$\mathcal{B}_{\operatorname{cc}}$ on $X$ and its conjugate brane
$\overline{\mathcal{B}}_{\operatorname{cc}}$.
