If one thing latches onto another, or if it latches on, it attaches itself to it and becomes part of it. These are substances which specifically latch onto the protein on the cell membrane
If someone latches onto a person or an idea or latches on, they become very interested in the person or idea, often finding them so useful that they do not want to leave them. Rob had latched onto me. He followed me around, sat beside me at lunch, and usually ended up working with me Other trades have been quick to latch on