Sources close to the discussions say PayPal is closing in on a deal to buy Braintree Payments Solutions, The Wall Street Journal is reporting.

The deal could put the online payments giant square in the center of the growing mobile commerce market, the Journal said. Acquiring Braintree would give PayPal access to data and transaction fees from Braintree's expanding network, which currently processes more than $10 billion annually and charges merchants a 2.9 percent commission and 30-cent transaction fee, according to the report.

Learn more about in-app payments.