Hi Sabuj, According to my experiments, the tube gets the color of the C1' atom in the sugar. Thus first color the C1' atoms the desired tube color, e.g. with the command color hot pink @c1' or, for different colors for different residues color dodger blue :7.a@c1' (residue 7 in chain A) etc. and then use the Nucleotides tool to generate the representations with tubes. I hope this is what you had in mind. Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html