Functional microarrays study:
Functional protein microarrays are constructed by spotting individually purified, active proteins onto surface retaining native conformation and activity. They enable direct assessment of biochemical functions including enzymatic catalysis, binding to DNA, lipids, small molecules, and protein partners, as well as detection of post-translational modifications mediated by kinases or ubiquitin ligases. Unlike analytical arrays that measure abundance, functional arrays probe activity in a proteome-wide scale, facilitating characterization of protein functions, discovery of novel substrates, and drug target identification. They are unsuitable for studying DNA synthesis or RNA processing directly.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.