Below is a three-dimensional representation of the protein, CD4. I would like to know what the arrows and the thin wires between them mean.
The flat arrows are a cartoon representation of β-strands (one type of regular hydrogen-bonded secondary structure). The direction of the arrow is the direction of the amino acid sequence (arrow head pointing towards the C-terminus).
The thin wires are regions with no regular structure.
There are also two small green spiral ribbons in the foreground left and right, which represent α-helices (the other main regular secondary structure).