Gap-junction proteins, connexins are important cellular entities that regulate various facets of cellular physiology. The connexins constitute large family of proteins. The present book provides basic overview about various aspects of connexin proteins. The book has tried to touch the fundamental aspects of connexin family. This book will be useful to broad audience that includes under-and post-graduate students, research scholars, clinicians, etc. The reference section at the end of the book will be helpful for those who seek to know deeper details about this family of proteins.