Quins sign SA prop
The Quins have not disclosed the length of the 21-year-old South African's deal at the Twickenham Stoop.
Moving to French side Pau in 2015, Holenstein helped them remain in the top tier of French rugby.
Cameron is a promising young player who brings a huge physical presence both at scrum time and in defence.
He grew up in South Africa, Holenstein began his sporting career as a javelin thrower, before turning his attention to rugby by joining Pretoria Harlequins.
"I'm really excited to have joined Harlequins, when the offer came for me to join it was too good to turn down," said Holenstein.
I'm going to work hard and embrace this amazing opportunity that has been given to me.
"To be able to develop my game around the expertise of Joe Marler and Graham Rowntree is something I'm really looking forward to and I can't wait to get started."
In 2014 he played for the Sharks Under-19 team, where his path crossed with current Harlequin Tim Swiel.
Harlequins Director of Rugby, John Kingston said he is delighted that Cameron has opted to join Harlequins.
"He is a tough, uncompromising, physical individual who will create real competition for places at loosehead prop," said Kingston.
"He has been signed with a mind that he will be challenging hard for a starting birth in the not too distant future.”
Harlequins finished seventh in the 2015/16 Premiership season.
