AceShowbiz -

Robert Pattinson partied with Katy Perry along with Justin Bieber to celebrate the release of her documentary movie "Katy Perry: Part of Me". The threesome spent the Tuesday June 26 night at the Bootsy Bellows lounge in West Hollywood, which is co-owned by David Arquette.

They were joined by Selena Gomez. The group packed inside Bieber's $200,000 Mercedes Benz minivan. The Canadian star and his girlfriend still wore the same outfit they donned when coming to the movie premiere earlier in the day at the Grauman's Chinese Theatre.

Gomez rocked a flirty pink mini frock with feathered accents and a pair of Jimmy Choo sandals. Bieber matched her appearance by donning a pink jacket on top of his black t-shirt. Perry traded her red Dolce & Gabbana dress with a black Vivienne Westwood attire and Christian Louboutin shoes. Pattinson opted for casual jeans and jacket.

"Justin and Selena shared a table with friends," a source told JustJared about the after-party. "They were very affectionate the whole night, holding hands and sharing kisses." Gomez, 19, and Bieber, 18, are still underage for drinking in the U.S.

"Katy and Amber Heard, and Shannon Woodward, spent a good portion of the night sitting and chatting with them. Everyone was laughing and having a great time, taking pictures with each other and snacking on mini-cupcakes," the insider continued.

The day reportedly happened to be the opening of the club named after Arquette's burlesque dancer mother. Ashley Benson, Queen Latifah, Carly Rae Jepsen and Zelda Williams were also in the house. Emma Roberts, Chord Overstreet and Alex Pettyfer were guests as well, but they reportedly partied separately.

After the party, the Bieber group left the venue in the same car, but Pattinson was almost left out.