function roots_connection_types() {
  // Make sure the Posts 2 Posts plugin is active.
  if ( !function_exists( 'p2p_register_connection_type' ) )
    return;

  p2p_register_connection_type(array(
    'name' => 'article_to_company',
    'from' => 'article',
    'to' => 'company'
  ));
}
add_action( 'wp_loaded', 'roots_connection_types' );