Can Metamask pass a user's signed tx to an Abigen binding?

Hi. I have built a web3/js based front end that deploys and interacts with a contract where others can contribute ETH (a kickstarter-type contract). Everything works fine, with MetaMask kicking in for any payable transaction. I then built a front/back end app using Go. I deployed the same Solidity contract and ran it through abigen to produce the bindings. I can interact with the contract bind file only by hard-coding my private key, or passing it through the front end. What I can't find info on is how to integrate MetaMask with the bindings, so other folks can contribute to the contract. I'd very much appreciate knowing if this is even possible, and if so, could you point me in the right direction? I've got this far but I'm stumped!

Thanks very much

Adrian Fletcher