Added α and β to clarify the naming of the separate chains.

Changed to :

{{c1::Integrins::Type of proteins}} have {{c2::two membrane-spanning chains: α and β ::structure}} and permit cells to {{c3::adhere to proteins}} in the {{c3::extracellular matrix}}.

Thank you for the suggestion. We do ask, and require, that an MCAT-specific source citation be included with any and all content-related suggestions, in order to streamline the process of suggestions and deck maintenance. More information can be found here: https://community.ankihub.net/t/anking-mcat-deck-submission-guidelines/384726

Please let me know if you have any other questions. :-)