13G Filing: Portolan Capital Management and U.S. Auto Parts Network Inc. (PRTS)

CUSIP No. 90343C100

1.

Names of Reporting Persons
Portolan Capital Management, LLC

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
2,068,553

6.

Shared Voting Power

7.

Sole Dispositive Power
2,068,553

8.

Shared Dispositive Power

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
2,068,553

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
5.97%

12.

Type of Reporting Person (See Instructions)
IA