Structural protein involved in the filamentous cross-bridging between microtubules and other skeletal elements. 3 different light chains, LC1, LC2 and LC3, can associate with MAP1A and MAP1B proteins. Interacts with guanylate kinase-like domain of DLG1, DLG2 and DLG4. Binds to CSNK1D. Interacts with TIAM2 (By similarity). MAP1 light chain LC2: Interacts with ELAVL4 (By similarity). Brain, heart and muscle. Expressed late during neuronal development appearing when axons and dendrites begin to solidify and stabilize their morphology. The basic region containing the repeats may be responsible for the binding of MAP1A to microtubules. Phosphorylated by CSNK1D. LC2 is generated from MAP1A by proteolytic processing. It is free to associate with both MAP1A and MAP1B. Belongs to the MAP1 family.