GPG, of course, allows you to use asymmetric crypto and currently supports RSA, RSA-E, RSA-S, ELG-E, and DSA algorithms for that purpose.
But for bulk data encrypting good symmetric (AES, CAST5, etc.) is both more secure and significantly faster.
But for bulk data encrypting good symmetric (AES, CAST5, etc.) is both more secure and significantly faster.
This is how the same document can be encrypted for multiple recipients efficiently, without duplication all the data. First the document is encrypted with a symmetric key, which is then encrypted with the public key of each recipient. This information will be prepended to the actual encrypted document.
For details see: https://tools.ietf.org/html/rfc4880#section-2.1