Involved in the biosynthesis of ADP-glucose building block, required in the biosynthesis of maltose-1-phosphate (M1P) and in the elongation reactions to produce linear alpha-1,4-glucans. Catalyzes the reaction between ATP and alpha-D-glucose 1-phosphate (G1P) to produce pyrophosphate and ADP-Glc. alpha-D-glucose 1-phosphate + ATP + H(+) = ADP-alpha-D-glucose + diphosphate Glycan biosynthesis; glycogen biosynthesis. Inactivation of glgC shows a strong reduction in alpha-glucan content. Combined inactivation of both glgC and treS results in a complete absence of alpha-glucan. Maltose-1-phosphate (M1P) is generated by two alternative routes: the TreS-Pep2 branch and the GlgC-GlgM branch, however it seems that the GlgC-GlgM branch provides most of M1P for the GlgE pathway in M.smegmatis. Belongs to the bacterial/plant glucose-1-phosphate adenylyltransferase family.