Microtubule-associated protein 1 subunit expression in primary cultures ofrat brain

Microtubule-associated protein 1A (MAP1A) and MAP1B are developmentally reg ulated proteins linked to axon formation, They each consist of a unique hea vy chain and three common light chains. We used immunofluorescence microsco py to qualitatively assess the variability in MAP1 subunit expression betwe en individual cells. The ratio of light chain 1 ito MAP1 heavy chain varies greatly between cells with some cells expressing MAP1A heavy chain in the apparent absence of light chain 1, The results imply the existence of MAP1 molecules that differ in light chain composition. Transfection experiments indicate that the light chains differ in microtubule binding activity and s ubcellular targeting activity. This further suggests that the regulation of MAP1 light chain content can control MAP1 function. (C) 2001 Elsevier Scie nce Inc.